load up your motorhome just as you would for a trip including full fuel, fresh water and lp tanks. waste tanks empty. food, clothing, pets, supplies, and people...don't neglect people. get individual axle weights and be sure each is carrying a load less than the corresponding gross axle weight rating.
the amount of weight you can safely tow will be the lesser of the following:
- the gross combination weight rating of the MH minus the actual weight of the MH as it is loaded and configured for travel
- the weight rating of your hitch
- the weight rating of your tow bar
with a full tank of fuel but otherwise empty weigh the vehicles you want to tow. you don't need individual axle weights. then apply the above tests.
good luck.