I've seen some units where people transport motorcycles on a platform that fits into the trailer hitch mount on the back of a motorhome, and they're not cheap. Personally, I don't like the idea of my bike being subjected to allllllll the dirt and roadspray that comes up the back of a motorhome when the weather is not perfect, and it won't always be perfect.
Decide for youself how much you want to spend, how much your bike means to you, but also how much weight some enclosed trailers are.
Here's what I use..............there's nothing better.
Enclosed Trailers for Motorcycles and Snowmobiles - Toy Carrier