The Forest River Work and Play Toy Hauler is the only 5th wheeler I am aware of that will accommodate a "Cobra". They are built on a cargo trailer platform. I own a 38FK. It has an 18' garage and 20' of living quarters. I tow it with a 2000 Ford F350 7.3L diesel dually. Fuel mileage is 10.5 to 12.5 mpg, depending on whether the cruise control is set on 60mph or 72mph. This rig is very spacious for bachelor travel - would be pretty cozy for a couple. I have done some pretty long hauls with this rig and I absolutely love it. You might check out the SL series - larger garage and larger living quarters with a slide.
http://www.forestriverinc.com/nd/def...hoice=brochure