Can you put a 5 gal can on your trailer tongue platform? If the tongue is long enough, you might be able to put a double hitch on the SUV (two receivers, one above the other), add a cargo carrier and put your gas on that. Harbor freight has both products. Have to be careful that the trailer and cargo carrier don't touch each other in turns.
2004 Tiffin Allegro 27.5 ft. P32 18,000 lb GVW. 8.1 liter. Workhorse chassis built May 2002. 21,000 miles. 2012 Jeep Liberty Toad. RVi2 brake unit.