I think diesel is a good way to go also if you really want a rig that big (currently I have an F250 w460, a real gas hog, but its paid for!). For your towed weight a smaller rig would do the job however. As a reference I'd recommend Trailer Boat Magazine. They have a towing reference section every year that gives the tow ratings for all popular vehicles and a column where they answer towing questions. Learned a lot there over the years. One other factor to keep in mind is to pay attention to the GVWR when choosing your tow vehicle. Basically this means that you add the weight of passengers/cargo to the tow vehicle and towed load. And then for reliability you want some margin. Without looking it up, I'd guess from your description you're pushing it with the minivan...transmissions have been historically problematic, my wife's went out at 40k and its never pulled anything but a drift boat, and that not very often. Happy shopping.