Based on your previous posts about the van, you’re not looking at TCs and trucks that are anywhere near new or nice enough to pass the 10 year rule.
But to answer your questions, to haul an “average” TC , figure 3500lbs min and tow a 4klb trailer (boat is 4k or the whole giddy up is 4k? Sounds light either way for anything live aboard. ) you need minimum 3/4-1ton truck. Any of them will do and a gas engine will do that at seal level on flat ground where you’re at.
Can’t help with the rest of the dilemma/story. Not familiar with the area.