Toyota requires a weight distribution hitch for your Tundra when towing an Oliver, we use the Anderson hitch. As you've mentioned your payload will be limited with the Tundra, visit a CAT scale and check your weights especially the weight on the rear axle. If you have the air bag suspension the truck will trim out nicely when towing the Oliver. The Tundra tows the Oliver very nicely and with the Tow+ mode and the twin turbos you'll get good performance. I've noticed no sway whatsoever with my setup and gas milage is reasonable at 13 mpg typically when towing ( 20mpg when not towing ).
We have the composting toilet and are glad to have it. We can go three weeks between changing out the compost which is easy to do. You'll save a lot of water by going with a composting toilet and not have to deal with other peoples messes at the dump stations.
Twin beds are the way to go with the Oliver.
Water conservation is key when boon docking but you can easily add portable jugs of water to the system if you need to by using the Olivers boon docking configuration.
The platinum lithium package is wonderful.
The pantry can hold a surprising amount of food.
We went with the 30lb propane tanks, they are heavy but came in handy for winter camping.