The 5th generation Dodge Caravan makes a good campervan for 1-2 people and will get 30 mpg on the highway @ 65 mph. My wife and I have rented one from Escape Campervans 4 times for a week each trip when we were visiting National parks in Utah, Arizona, and New Mexico. We averaged about 26-28 mpg in a mix of interstate, state highway and dirt roads. Steady state cruising got the instant MPG into the low 30s.
The Caravan is nice because the stow n go adds extra space. Escape's conversion pulls the middle bench and replaces it with a storage area over the stow and go. That triples as a bench seat and bed. They left the rear bench in place to legally carry passengers. The kitchen was behind the rear bench. Slide out fridge, stove, sink and some storage. The fresh water and grey water tanks were in the rear stow n go.
Personally I wouldn't waste space on a sink and grey water tank in a rig this small. The sink is too small to do anything. For my Astro Campervan we just use a water jerry can with spout.
Escape replaced their Caravan vans with Transit Connects they call the Santa Cruz. (It has a fixed bed and a slick pull out kitchen)
Juicy has the same set-up as the Escape Caravan we rented. Juicy's Youtube video of their van features:
Kitchen
