Hi Bob Ben,
We went from a 13 foot Boler (Scamp) to a 22 foot FunFinder. Mileage dropped about 4 to 5 mpg when using the same tow vehicle, which was a full size pickup. The bigger camper definitely pulls harder, but the upgrade was well worth it.
2012 Chevy Silverado 1500 with factory brake control
Equal-i-zer 600/6000 hitch