My fantasy vehicle would be modeled after a RoadTrek Van--I have a 2001 190V currently. I can even get 18 MPG with it if I keep the speed @ 57 MPH.

But my fantasy RV would be a fuel cell camper Van.

Camper Van is best because I don't need all the wasted space & I can drive & park where the bigs ones can never go.
With a fuel Cell(s) the waste heat & water could be utilized for water heating & water "making". All appliances (stove, fridge, etc.) could be electric for simplicity. Besides the fuel cells, power would be stored in several 'flywheel batteries'--a mechanical battery with many times the watts per pound of current lead acid or even lithium ion batteries. High Efficiency solar panels on roof & awning(s) and extensive use of LED lighting. Toilet would be a slightly heated & vented compost type so no black water tank would be needed. All windows would be Low-e glass and double pane where possible. What do you think--is this too big of a fantasy?