RE: Boulder Creek RV Resort and Ancient Bristlecone Pine Forest
Staying in Bishop would be your best option considering what you plan on seeing, it would definitely cut down on driving mileage. I suggest Highlands RV. I have been to all of them.
RE: Fuel tank recommendation.
Try https://kshmarine.com/ they are in Lake Havasu, great products I have a 75 gal in bed with tool box that they built to my specs many years ago. They have lots of products or will build.
RE: Brake Pads
my last 2 trucks when the pads wore out the rotors were close to minimum
thickness and I prefer thicker the better for heat dissipation.
RE: Brake Pads
I think I'm going with the Akebono Euro Ultra Premium pads and NAPA premium coated rotors upon recommendation of a pro mechanic that also tows heavy.
RE: TPMS - lock nuts on caps?
I use a crowsfoot with an 6" extension to tighten my inner locknuts. Get your inner valve stems changed so they angle thru the hole correctly
RE: Mazama and Sumitomo tires
They have not split from Toyo, my local Schwab dealer is currently going to order me a set of Open Country at 3s they are on backorder. I had the open countries put on in a hurry up affair while on vacation and I'm trading them in on there 60 days trade off, they are under rated for my application and don't seem as stable towing as my old Toyos.