I've found both KEH and Roberts Photo's Used Photo Pro both to be reputable and honest sellers of used cameras and lenses.

Might as well bite the bullet and get a Nikon D850... currently the best DSLR for virtually all types of photography. I replaced my D810 with a D850 and much prefer the D850. Get it refurbished on the Nikon site (nikonusa.com) but wait for one of Nikon's periodic special 10% off refurbished products sale, usually around holidays like 4th of July, Labor Day, etc. etc. Sign up for Nikon emails and they'll let you know when they have a sale. I bought my D850 refurbished from Nikon and it had about 25 clicks on it when I got it. Also bought refurbished Df, speedlights and many lenses and never had a problem with any of Nikon's factory refurbed products. Have fun... the D850 is a great camera and you'll love it.

The easiest way I remove stuck lens filters from the lens is to wear a Playtex Living Glove on one hand, grip the filter with the gloved hand and twist. It works every time for me, and now I carry a Playtex Glove in my gadget bag "just in case."

The absolute best way in the world to clean a camera lens video... https://www.youtube.com/watch?v=dBTb1l0jLIw

You don't mention what camera you own or what lenses you use, or how heavy a load you typically carry. But I've been very pleased with UpStrap-Pro camera straps for my Nikon D850 and a 2-3 pound lens. UpStrap features a non-slip "sure grip" shoulder/neck pad that stays in place and is easy on the neck. UpStrap camera straps are made very well and offer different styles depending on the weights of the camera and lenses you're going to use it with... plus they're actually made in the USA. http://www.upstrap-pro.com/

UpStrap http://www.upstrap-pro.com/

I'd bring the D5300 and Sigma... just in case you run into DJT and have a chance to get some good photos!

Check out the Nikon Df... accepts Nikkor lenses back to the 70's and resembles a Nikon F. Save money by buying a refurbished Df on nikonusa.com... https://www.nikonusa.com/en/nikon-products/product/refurbished-dslr-cameras/nikon-df-refurbished.html

I recently inherited my father’s collection of more than 5,000 35mm slides from the 1947 through 1996, including tons of shots of my brother and me growing up in the 1950s and 60s I purchased a Nikon slide adapter to use with my Nikon D810 and Nikkor 60mm f2.8D lens and am in the process of sorting, selecting, shooting and editing the slides I want to keep and digitize. While very time consuming it is also very rewarding to take 70 year old slides and convert them to digital for easy storage and viewing and sharing. Attached are some photos of me as a kid...

I watched the online Nikon Z6/7 Hands-on Panel Discussion (twice) as well as watched or read user reviews on numerous web sites, but I still don’t understand why I should want or need this new mirrorless camera. I currently own a Nikon D810 and two Nikon Df’s along with a variety of AI-S, D, G and E lenses. What are the compelling reasons why I should add this camera to my current Nikon product collection or replace one of my existing cameras? And if for some reason I need a mirrorless camera, wouldn’t I be better off buying a Fujifilm XT2 with a Nikon F mount converter?

I recently purchased a RAVPower EN EL15A battery from Amazon during the Amazon Prime Day sale. It came with a USB charger, connecting wire and two batteries. It took about 2 hours to charge each battery, both batteries fit perfectly into my D810, were recognized by the camera and indicated full charges. The batteries also popped-out of the D810’s battery compartment easily and without issue. So far I’ve only taken about 250 shots with one of the batteries (including using the pop-up flash), and the battery I’m testing seems to be holding its charge. After four days’ storage in the D810, I’ve lost one bar on the camera’s battery meter. So... so far so good with the RAVPower. I also like the RAVPower battery charger which allows charging of two batteries simultaneously.

I’ve used KEH both to buy and sell gear. Their product descriptions on the “buy side” are accurate and reliable, and if anything are a tad conservative... i.e. items graded as “excellent” in many cases are more likely “excellent-plus” on delivery. Orders are processed quickly and are packed securely. Seems like a reputable company based on my experience. Sign-up for their emails and they periodically have 5-10% off coupon offers.

To enhance your Route 66 driving experience and inspire your photography, make sure to get recordings of the “Route 66” songs to play on the road, including the classic Nelson Riddle “Route 66 Theme” orchestral played on the old TV series as well as versions of the rock song “(Get Your Kicks On) Route 66” by The Rolling Stones, Chuck Berry and Nat King Cole. And hit the sites mentioned in the song: “Well it goes from St. Louis, Joplin Missouri, Oklahoma City looks oh so pretty, You’ll see Amarillo and Gallup New Mexico, Flagstaff Arizona, don’t forget Winona, Kingsman, Barstow, San Bernardino... Get your kicks on Route 66!” I drove cross-country from New York to Phoenix in 2002 and hit parts of Route 66 during my three and a half day drive. Of course, your trip would be especially memorable if you happen to have a 1966 Corvette!

Also, once you find and can read the serial number, you can visit this site to discover approximately when your lens was produced, where it was produced and how many were produced: http://www.photosynthesis.co.nz/nikon/lenses.html

...a flashlight will help “light up” the laser engraved serial numbers on the back side of the aperture ring...