TRUST is an arbitrary term. Look at it this way, a NEW camera is NEW, no questions asked.
But used is a different animal altogether.
A company can give a used camera a 7 rating, or a 10 rating, and each company will explain their rating system. But KEH's 9 is going to differ from a 9 at B&H, because rating's are arbitrary by their nature.
I only trust MINT IN THE BOX when I am shopping for USED equipment.
Case in point, I recently bought a Sony a9 with vertical grip off ebay MINT IN THE BOXES with an extra battery for about $2300.00. The body had a shutter count under 2000.
Everyone can understand MINT, it is not a number, but a condition of being.
And, once I receive it, if it is not in MINT condition, I can return it, now, B&H and KEH also offer a excellent return policy.
But for me, trust does not enter the purchasing decision. I want a guaranteed no questions asked full refund policy. B&H and KEH both have them, as does Ebay.
And, if you have questions, you can call B&H and KEH and ask them to put the camera in their hands and describe it to you live over the phone.
MINT and a low shutter count for me.

NO, but the whole concept is difficult to grasp.
Look at it this way, a DX lens is designed to cover a SMALLER sensor, a DX lens is designed specifically for a DX (cropped sensor body). A FX lens is designed to cover a LARGER sensor. I hope you follow this so far.
SO, if you put a DX lens on a FX body, it will not cover the LARGER sensor of the FX body and you will get vignetting in the corners of the sensors. BUT, if you put a FX lens on a DX body, the FX lens will actually spill over the coverage of the DX sensor BUT can still be used, BUT, you can only use the center of the FX lens because at over covers the corners of the DX sensor.
NOW, this is the confusing part, ANY lens on a cropped sensor camera has a crop factor of 1.5, that is for ANY lens you mount on a crop sensor camera.
Look at this lens from B&H, the Nikon DX 18-200, look at how B&H describes the angle of view, they say,
"27-300mm (35mm Equivalent)". They are trying NOT to confuse anyone, but what they are actually saying is that on a CROPPED DX body, the lens will have an angle of view of 27-300 mm.
https://www.bhphotovideo.com/c/search?Ntt=nikon%2018-200&N=0&InitialSearch=yes&sts=ma&Top+Nav-Search=
So, any lens put on a DX body is going to receive a cropped 1.5 effect. (For either a DX or FX lens.)
So, getting back to your statement. A DX 24 mm lens on a cropped sensor camera actually has a field of view of 36 mm, not 24 mm. Any lens you mount on a DX body, either a DX or FX lens, will get a 1.5 multiplication field of view factor.
OK, the other part is this, the DX body does not see, it can only respond to any lens put on it, so, the DX 24 mm lens (which by the way does not exist) on a DX body will yield a field of view of 36 mm. And yes, a DX lens is designed to go on a DX camera, that part you understand.
The only confusing part is that you just have to except the fact that ANY lens put on a DX body will receive a 1.5 increase in it's field of view. ANY LENS.
I probably confused you further but I tried, still have not drank my coffee.

A DX 24mm lens on a crop body would have an angle of view of 36mm. So, basically, YES.

Your using UHH members, responsive and responsible in the same sentence, now that is hilarious.

Coffee and shower before I go to UHH tomorrow morning. I messed up on two other sites also. Bad day all around, BUT, good day for fall foliage around the lake, very cold, wife wants to go South today but talked her out of it until Monday.

MORE COFFEE.

Really, and what FACTS do you base your answer on.

Not enough coffee yet. My bad. I fixed it. thank you.

Nikon will have sales again BLACK FRIDAY, CYBER MONDAY, and over the Holidays. They will usually throw in a vertical grip, usually the best prices are from Black Friday into the Holidays. But Nikon has sales several times during the year and also put different lenses on sale at different times of the year.
I still own my 18-200 II mm lens, if you still own that lens their is no need for the 18-140 as the 18-200 has the greater reach. I would get the II version of the 18-200 if you currently do not own this lens.
You can still find early 18-200 lenses that were produced in JAPAN before production was moved off the island.

Found a very good, sharp, Nikon 85mm 1.8 D lens for $250.00.
https://www.ebay.com/itm/Nikon-AF-Nikkor-85mm-F-1-8-D-Lens-With-Box-24278/163925048856?hash=item262ab1be18:g:Ni4AAOSwavRdulOW

Found a D7000 body for $219.00
https://www.ebay.com/itm/Nikon-D7000-16-2MP-Digital-SLR-Camera-Black-Body-Only/293306514312?epid=100112575&_trkparms=ispr%3D1&hash=item444a6e3b88:g:gx0AAOSwOxJdu3ls&enc=AQAEAAACQBPxNw%2BVj6nta7CKEs3N0qXB7yMMaIhoU8odyWlORL30smkwa5e8cSUbOrRpxerinLkBLXe16NiHPFfCWFaw9LVBa5q4ggcxacn1a23CmMrKvLmuvnl6O7UA%2Fmo6Vjuzs4EeF74ZaPHT7v3WpEinWkR5HjvZ5syq9qKiAiD7PlJ5L4G3qBzg1OHmd9xLXMNhC7p5jLJdjDWKmOaw8TQVFxOJ0X0fyHCmf0q8vTYJ9CVVxtLgjomTULchPb90acAi913AfIaZMPjVJ04OJfCyIfrz8ltyd96wE3NNQ36bPWpmtFLWxFrDvnlxmwZkrXMN1BfYGSVyA%2BL1ugSLefeIl9oGa9Q%2BM6LqxBepc3a6W1ypnmsIcdXF3RQzda9V13O31FGt7oOIQNEvpPGHu2lfDpm%2BpUb%2BL4vLQ08Kg2q4cGt22yZWx0TcfBt66ALsg0QBmFk4gF97Ah3gqotQEE8FaVY%2B6%2BrhiUENKI%2F%2FhUrYJo%2BwGq2s1K%2FA5JUQLdcCxAyP7wsS3LzoKxZfgVHYXUd5sQvu6HLDR8FHOXEvDGoRP6nPunG02vDuSNkqQeJ%2FwJjeOMFp9caw4FwUvRjjfDg%2FJqOk%2FxbZmF8uuOl%2FUBW72aLjCsAyRXr%2FFmaKzLWjA8vgHtEYOZvHGVt3%2BdOOmssp%2BcwYacDeXa0A227ydTaFkbKD2eru0oH16X2yIysdsJlyide869iOtptJsm%2BZuSvQQDyr%2BFSmljpLj54Q5g4xvsTv0%2FULFOSSk3Is8Yh%2BJOlSdg%3D%3D&checksum=2933065143126301c14d2a7f42679a5fe91d27935e15&enc=AQAEAAACQBPxNw%2BVj6nta7CKEs3N0qXB7yMMaIhoU8odyWlORL30smkwa5e8cSUbOrRpxerinLkBLXe16NiHPFfCWFaw9LVBa5q4ggcxacn1a23CmMrKvLmuvnl6O7UA%2Fmo6Vjuzs4EeF74ZaPHT7v3WpEinWkR5HjvZ5syq9qKiAiD7PlJ5L4G3qBzg1OHmd9xLXMNhC7p5jLJdjDWKmOaw8TQVFxOJ0X0fyHCmf0q8vTYJ9CVVxtLgjomTULchPb90acAi913AfIaZMPjVJ04OJfCyIfrz8ltyd96wE3NNQ36bPWpmtFLWxFrDvnlxmwZkrXMN1BfYGSVyA%2BL1ugSLefeIl9oGa9Q%2BM6LqxBepc3a6W1ypnmsIcdXF3RQzda9V13O31FGt7oOIQNEvpPGHu2lfDpm%2BpUb%2BL4vLQ08Kg2q4cGt22yZWx0TcfBt66ALsg0QBmFk4gF97Ah3gqotQEE8FaVY%2B6%2BrhiUENKI%2F%2FhUrYJo%2BwGq2s1K%2FA5JUQLdcCxAyP7wsS3LzoKxZfgVHYXUd5sQvu6HLDR8FHOXEvDGoRP6nPunG02vDuSNkqQeJ%2FwJjeOMFp9caw4FwUvRjjfDg%2FJqOk%2FxbZmF8uuOl%2FUBW72aLjCsAyRXr%2FFmaKzLWjA8vgHtEYOZvHGVt3%2BdOOmssp%2BcwYacDeXa0A227ydTaFkbKD2eru0oH16X2yIysdsJlyide869iOtptJsm%2BZuSvQQDyr%2BFSmljpLj54Q5g4xvsTv0%2FULFOSSk3Is8Yh%2BJOlSdg%3D%3D&checksum=2933065143126301c14d2a7f42679a5fe91d27935e15

So, that 85 mm would give you an angle of view of 127 mm on the D7000. $469 total investment.
Good luck and keep on shooting until the end

Have you called your tour company for their recommendations? THEY know how close they will be to the wildlife, they know where you will sit in the vehicle, they know what time of day will be most productive for wildlife viewing. (so you will know in advance what ISO you will most likely need)
All tour companies have different routes and have (reservations) for being certain places at certain times. Call THEM, they know the answers to your questions because they do it every day of the year.

A FX 24 mm lens your D750 has a field of view of 24 mm. A FX 24 mm lens on your D7200 and D5300 has an field of view of 36 mm.
A DX 24 mm lens on your D7200 and D5300 will give you a field of view of 24 mm. A DX lens on a FX D750 camera is not recommended.

Interesting post in light of those that say DSLR's are dead. Evidently the news of it's death have been greatly exaggerated.
The Nikon 500 5.6 is still on a wait list after more than a year into production (demand remains extremely high).
When the D850 came out it took over a year to catch up to demand. The D500, D750, and D610 continue to sell. In a recent survey those that bought the D500 say they would buy a second, no new model needed. The D500 with the Nikon 200-500 has become the standard for many into wildlife photography.
And now, an $8,000.00 lens is over sold. Yet the masses clamor to the fake news that DSLR's are past their prime. Interesting post.

Congratulations, you are only $7997.63 from your goal.
PS. You may need a bigger piggy bank.

You need to be more, "on the level" grasshopper.