I think I did pretty good this past weekend by getting 18 mpg with the Jeep and our ~2600 lb Fleetwood Evolution E1. This is as good as got with my YJ by itself!
On topic, we LOVE the E1. It was very reasonable in price, and is kinda like when I went from my YJ to the JK in terms of comfort going from camping off the GS to glamping with a camper. Maybe having a baby wasn't such a bad idea.
Admittedly I keep it at around 60 mph with the 55 mph limit in Kalifornistan.