A previous motorhome was a 38fter with a 454. We towed a mid-sized olds wagon on a towdolly and almost all of our trips were through the western mountains. I think you will be ok however don't expect any speed going up hill in the mountains. If I remember correctly, I drove the steeper grades in 2nd and 3rd at 35 to 40 mpg or less, and sucked fuel. A 5k hitch was pretty standard. I bet a good hitch shop can rate it for you. Get good brakes on the trailer, I believe required in Canada, because the disk brakes on the motorhome just won't cut it on the mountains.