has anyone used a diesel van as a tow vehicle? i have an old airstream that i am restoring, and the wife just informed me that my truck is too rough and loud for her to go on roadtrips with me! also, my truck is just a single cab.. and with junior on the way, that wont be a fun ride so, i'm wondering what kind of mileage a diesel van would get towing a trailer(comparable to my truck, which gets over 15mpg), and how they fair towing a trailer in general. also wondering if the 4wheeler will fit in the back(which is a must-have option) any thoughts on this??