I have seen folks use something like the Rage Sport to carry small motorcycles off the hitch of their motorhomes.
Rage PowerSport Motorcycle Carrier with Long Ramp and Aluminum Track for 2" Hitches - 600 lbs Rage Powersports Hitch Cargo Carrier SMC600
Two things you need to consider
First is the weight. The weight of the moped and carrier should not exceed the maximum tongue weight of the motorhome's hitch.
Second, if you plan on driving the moped on streets the laws within the communities you are travelling to. For example, some states do not require a license for 50CC or under whereas in Virginia, since July 1, 2014, any moped being operated on public roadways must be titled and registered and if it is operated over 35MPH a motorcycle drivers license is required as well as all safety inspections, taxes etc...