That would be a heck of a vehicle. you've thought it out well!I’ve spent literal hours figuring out what I’d tell a Toyota R&D exec if I ever somehow ran into one. A SRW 1 ton and a 1 1/2 ton, also optioned with SRW with a setup similar to Buckstops conversions for 4500 & 5500 trucks, with a a 10 speed and 4.30 gearing with manual locking diffs, engine brake, and two engine options - gas and diesel, both inline 6s and make the gas a turbo as well. Onboard factory air with rear bags and enough cfm to run air tools off of the extra hookup. Factory available engine driven hydraulic utility flat bed with dump and bale arm options. And the list goes on.
I plan on eventually breaking down and learning how to build my own version of this on an 04-09 Ford 5500 chassis with a 12 valve dropped in.
The current Tundras are really built to be 3/4 ton in the shafts and drive gear but the suspension is what limits them. Dead nuts reliable with a great proven engine but it is what it is. A 1/2 ton rating.