I've been to every place that you mentioned in a gas RV (36' Winnebago Adventurer) and I've towed a car behind our RV when going to these places. My engine is a Chevy Big Block 496 CI, 8.1 Vortec and if I choose too I can go up any mountain pass 55 MPH plus towing my car. There are also gas engine kits ( Gale Banks) that you can have installed to give you extra horsepower if desired at a cost around $2,000.00. Ford also makes a gas V-10 Triton that is just as good as a Chevy (I know this because I've owned both) I don't know where you got your information from on gas coaches, but IMHO I feel that you have been misinformed!