Best of luck in your search--
Remember, not too many folks walk into a RV dealership with a pocket full of cash. If you find something you "can't live without", make a ridiculously low offer- You can always go up- Be tough!
Oh, we all knew what you meant with your "Class 3" comment.
We've had quite a few campers come into the Campground we stay at in Maine in the past few summers, that are in Itasca "Navions" or Winnebago "Views". They have a Mercedes Diesel engine and they claim they get 18-20 MPG.
That's more than twice what many of us get--
Good luck, and please keep us posted on your progress--
2002 Newmar Mountain Aire, 37', 3778, W-22, 8.1 Vortac, Ultra Power upgrade, CAI (cold air intake), Taylor wires, colder plugs, Koni shocks.