I believe if you want to spend the $$$ you can get a hitch. I seen a KZ that had a swivel trailer with a large Harley. Was very professional, it was build very strong. If I had know we had the option to have a factory rear hitch I would have gotten one on our MS . GBY....
Here is a list of states you can double tow (they call it triple). If I am not mistaken you also have to have a class A license in California.Well we found out that they will stop you in Oregon for pulling a trailer behind your 5er. As we were leaving Coos Bay, OR this morning a trooper pulled us over and asked if we were aware you can only pull one vehicle behind a pickup. He let us off with a warning this time and let us continue to the Calif. border. Apparently Wash. and Oregon are the only states west of the Appalachians that have a problem with it. Guess we won't be coming back to these states anytime soon.