If you're still using LR3 you're missing a tremendous range of very powerful features that have been added over the years. Lighten up and see what LR really does now.

If you're expecting birds roosting or sitting then the tripod and 100-300 is probably as good as you can get. After several years of working on shooting pics of birds in flight my experience is that its VERY difficult to keep the focus point on the bird image which even with 300 mm is going to be very small and, while panning to track the bird you will, most likely, have the bird off the focus point rather than on.
So
1 - forget the tripod
2 - keep the shutter speed at 1/1500 or higher to compensate for camera shake.
3 - set in AI Auto and also highest speed of repetitive photos.
4 - if your can set the parameters for the Ai auto, slow down the speed of the camera trying to acquire another focus point or shoot with 1 focus point only. The camera jsut doesn't keep up with the bird moving on and off the focus point
5 - keep the aperture as small as you can to give the greatest depth of field.
6 - set up back button focus so that you can easily freeze the focus point when it makes sense

Put all of these settings in one of your "Custom Settings" spots so that you can quickly switch between an inflight mode to other modes for shooting other scenes.

Depending on the tour you've booked, you will be taking almost all of your photos from a seat in a jeep type of vehicle. Again, depending on the tour you very well may be sharing this seat with another guest or worse, another photographer. By far, most of your photography will be in relatively full daylight as most of the game drives are back in camp before full darkness and don't leave before sunrise. Your biggest challenge will be schlepping all that gear around. Keep in mind the back of those jeeps is a pretty rough ride both on you but more so on your gear
On 2 trips to Africa I did 95% of my shooting (I shoot Canon) with a 100 - 400 with the 1.4x teleconverter. If you want to carry a second body or a second lens I use the 24-105 that I can have in my photographer vest.
Shooting conditions are often very fluid. Most of your shots will be at significant range but invariably the opportunity will arise with a game animal within a few feet of you in the jeep and the long lens is too long but you won't have the time to change lens. For the few shots in low light I just up the ISO. Never had to go above 4000 or so so my 5D IV does just fine. Or use auto ISO - again the dynamic conditions will put you at a disadvantage if you need to stop to change camera settings
By and large I keep the speed above 1/1500 and IS on all the time. The jeep even when parked is not a stable platform with people moving around all the time.
Schlepping lots of equipment can become a major hassle.
FYI - don't expect to use a tripod in the jeep. You won't have room for the legs. I also bring my 16 - 35 for the rare wide angle which if your going to shoot pics of long lines of wildebeast is useful.

LI batteries can exhibit a failure mode where the internal materials are swelling. Can be leadibgto a short and over heating and fire. I'd say bag it. It's not worth the risk

There's a new sunset everyday. Maybe not all mind blowing. However, last night in the SF Bay area there was one of the most mind blowing sunsets I've ever experienced. First off it was quite late. At this time of year the sky is generally dark by 5:30. But At six last night the entire western sky, north to south was ablaze in an intense orange, but not just along the horizon but way up 50 - 60 degrees above the horizon. But to make it even more unusual, the rest of the sky into the east was lit with broken clouds illuminated in a light magenta color which was reflected onto the surrounding hill sides turning everything into a magenta illumination. Sadly I was not able to get to a point of possible photos until the effect was gone but it did last for several minutes.

Subscribe but I also use On1 and am experimenting with Luminar. I like Luminar because it is simple to control the "punch" of a photo w/o having to resort to layers as in Photoshop.

Apple has had a historical animosity towards Adobe so its likely that any operational bumps brought on by Catalina would be left up to Adobe to solve rather than working together to smooth the path for customers. This then leads to divergent versions of software to address and support the 12% market share Apple needs vs. the 88% of needs in the rest of the world. Where would you put your development resources.
Its high time Apple consider the needs for all customers rather than expecting everybody to bend to their narrow version of the world.

My before and after were pretty dramatic. Before, the whole world seemed to be in a yellowish-grey haze and my depth perception was dangerously bad (multiple falls because I couldn't see things like curbs and steps that didn't have good color differentiation). After, the whole world was much brighter and more colorful and I stopped tripping over the obvious.

Many airlines will let you put a carryon "underneath the seat in front of you" if it won' fit in the overhead bins. My ThinkTank roll around camera case is 20"x13"x8". Depending on the airline equipment involved it may fit under the seat. Last Monday flying from Kalispell to Denver on a CanadaAir Regional jet 200 the case fit nicely under the seat and even left room for my feet. At 6' tall and a couple of extra pounds I didn't feel too compressed. SFO to Las Vegas is probably and hour and a half so squishing a little for that time is probably tolerable.
I can put my 5D IV with the 100-400 zoom and 1.4x converter in the center of the case and a 24-105 and 16-35 in the side pockets of the case and have room for lots of other accessories e.g. 600ex flash, lots of batteries, a Hoodman loupe, etc.
If I hadn't had my laptop in the case front pocket it would have fit in the miniscule overhead bin.

I just got back from Glacier Monday evening 9/9. As far as lenses go I used both my 16-35mm and 24-105 for landscape shots. In Glacier, you are often pretty close to some spectacularly high cliff like mountains so the extra wide comes in handy. Used a 100-400 with 1.4x teleconverter for wildlife shots much of which was pretty far out. While there are many turnouts along the Going to the Sun road often these were totally parked up last week. Sadly crowds and traffic jams.
Note that most of the hotel facilities in the park close about 9/22 so be sure you have accommodations. Facilities near the park entrances are pretty sparse..

For wildlife shooting I have found that my caneon 5d IV with the 100-400 zoom and 1.4x teleconverter is the best overall. Reaches out more than a quarter mile when needed but is short enough except when a lion or cheetah decides to brush the side of your jeep. Minimizes the need to even think about changing lenses. I do bring along my 16-35 for the daily sunrise/sunset shots or those vast open spaces with a miles long single file row of wildebeast. Don't bother with a tripod or monopod. Just gets in the way in the jeep which on most safari game drives you are confined to. While I bring along my whole case of gear set in a roll around on the game drives I use a Salvatore Bug Out Bag which is extremely useful when the time comes that you do want to change lenses. Brought along a bean bag but never used it. The jeep is never a stable platform unless you're the only one in it. Stand up, use your best shooting posture and keep the shutter speed above 1/1500 th with the stabilizer on. FYI. Bring along 1 or 2 cloth baby diapers. Good for light rain protection and, in the rare instance you may want to rest the camera on the jeep frame it provides a good pad. Then at the end of the day you can use it to wipe the day's dust accumulation away.