I would think 4:10 and stock size tires would help a lot. If it were me, I would use what ya got, if after the first trip you say never again, decide on something different.
#5 buy a diesel truck and a small camper put the small camper behind the suburban and your big one behind the truck. That way when you get there, your kids can stay in their own camper! Or substitute an enclosed trailer full of ATVs or a boat for the second camper, then you have more toys to play with when you get there. Just giving you more options to think about :)