You will find the people on this website knowledgeable and friendly. Having enjoyed the comments of my on-line friends for years I can say that you should not have a problem if you add some information to your profile. The type of RV, length, engine, year will help others answer your questions.
All of my previous motorhomes (MH) were gas. The mountains out here in the west can be a challenge. My older "big block" 484 GM struggled on the mountains with a tow car. The newer V10 and then the Workhorse 8.1 did fine on the grades pulling a 3000lb car but it really ate gas. I now have a diesel, which should handle a heavier toad but I've yet to try. At 4000+ lbs your toad is probably close to or over the combined weight rating of a gas MH. Adding a tow dolly or trailer will add another 500 to 1000 lbs to the combination. This may also exceed the weight rating of your hitch, even on a diesel. All things to consider in your new venture. Also, if your going to drive the western mountains, really consider a supplemental brake system...Really.
JMHO
