You don't say whether your RV is a travel trailer, 5th wheel, motorhome, or what. Depending on what your RV is, it may be more or less doable. I would think if it is a travel trailer you may have issues adding 250+ pounds in it when towing. You would probably want to place it directly over the axels when towing it in a travel trailer. A class C motorhome is probably not going to have enough cargo capacity available to add the weight, assuming you are carrying some amount of fresh water, propane, etc. A class A motorhome or a 5th wheel may have the available cargo capacity, but you are going to want to make sure it is strapped down very good for travel and, unless your RV is a toy hauler, it is unlikely to have good anchor points to tie down that kind of weight.

If you do it, report back so we can see what you did. I have thought about putting a machine in my RV, but I do not have slides and am very space challenged.