Supercharge my motor

You would be much wiser to start with a smaller engine that already has a turbo, such as Ford ecoboost. A turbo on a small engine makes much more sense for an RV. Turbos tend to be more efficient, and in a truck, you really are not concerned about turbo lag. A smaller engine will give you the efficiency, and the turbo will give you the power and torque. Because of the turbo, you end up with a flat torque curve, so plenty of guts to get you rolling. Ford's ecoboost is rated 365 HP and 420 ft-lbs of torque, which should be a pretty good match.