Get the truck first. Say you limit yourself to RVs that you think can be towed my the minivan. You freak out when towing after 2 trips and buy a truck. You can have a lot more RV at 5-6k dry than 2500 dry, and that will cost even more to upgrade the RV later.
7 foot wide by 9-10 feet tall is still far more frontal area even curved front than the 40SF rating.
No other trailer type tows worse than RVs. Not even enclosed cargo trailers. A TT is mainly a very large empty box, so relatively light for it's size. Besides pulling two sheets of plywood through the air at 60mph that needs quite a bit of power, you have 8 foot by however many feet long to catch any cross winds.