Hi Steve,
On my old Ford Ranger, the fuel tank was on the left of the frame and the right had the exhaust but there was ample room for a couple frame mounted batteries on the right of the frame.
A couple AGMs on your frame would be good as AGMs are better at handling the rough bumpy and imaginary roads that appear in many of your exotic trip reports.
Also, with a smart solenoid separating them from the truck battery, they would always be charged if you use the truck often enough without the camper on it. Some large battery cable from the alternator to the batteries and also to the TC electrical and you would have serious power available, don't forget to include the solar system.
Good luck on figuring things out.