IMHO, what Ford (or somebody) ought to keep on offering for the US delivery market and motorhome small Class A and Class C market is about a 20,000 - 22,000 GCWR van body with single or dual rear wheel drive and an engine sticking out the front a bit (to keep the step-up into the cab low) - that is a hybrid - with combined intermittent battery-boost/engine horsepower in the 350 range and combined intermittent battery-boost/engine torque in the 450 range ... and overall fuel mileage, when fully loaded, in the 12-14 MPG range.
This would replace the current Ford E450 class van with about the same type of vehicle, but with nicely improved fuel mileage while at the same time not giving up weight carrying capacity, towing or non-towing responsiveness, and overall ruggedness.
For me an "E450" Class C RV powered with an EcoBoost V10 and a lithium battery bank mounted down low alongside the frame members protected by steel road-shielding ... would do it!