The reality of this discussion is really difficult to grasp for an old trucker like me.
When I was first driving tractor trailers one of my tractors was a IH 450, with a 450 c.i. inline six cylinder gas engine and I pulled a dump trailer hauling at a GVW of 75,000# plus over the hills in Western PA every day. Moving up to a B Model Mack with a 205 HP diesel and a five speed main transmission and a three speed auxilary trans I thought I was in heaven. Even pulling maximum loads of fire brick into the steel mills of W PA and W VA.
Times have changed and now I am driving a 350 HP Cummins 8.3 pulling a Chevy Silverado grossing at about 36,000# and expecting it to accelerate like a car.
From a power/torque standpoint there isn't a motorhome made today that isn't capable of pulling almost anything we could hook behind it. The limitations are the strength and quality of the frame extensions and hitches used by the coach builder and the transmissions used by the chassis manufacturer. Common sense isn't all that common, but it is always useful when considering something we are pretty sure is a dumb idea from the beginning. I am always reminded of the person who says "Watch this" as he does something really dumb and we are amazed when they fail miserably.