Well... my pickup has only 350HP, but that still beats 318 HP in my 15 tons conversion.
Hard to compare, but main point is that even with 500+ HP in motorhome, the gas pedal is on the floor for most of drivers.
Try that with your truck engine and see how long it last.
Coming to Class A - you have humongous number of choices.
I choose my vintage bus conversion due to quality of materials and roll-over ratings. Others value cosmetics more than safety and reliability.
I think making your mind on those aspects should be starting point.
