Winnebago Electric Motorhome on a F-53 chassis

I own a 2011 Lincoln MKZ hybrid. It gets 37 mpg and the drivetrain technology is really refined. If a motorhome were to be designed like my hybrid; this is what it would look like. It would have a smallish gas or diesel engine, plus an electric motor, and a rather large battery pack. You would never need to plug it in. It would cruise the flatlands with the petrol engine, then the electric motor would kick in and help up the mountains. On the way down the mountain it would have regenerative braking to recharge the battery. The engine would shut off completely at a stop, but the electric motor would assist in getting up to speed when the gas pedal is pushed. No limited range. I think a hybrid system could work very well.