Carrying a scooter (motorbike, not mobility scooter) ?

I'm considering the possibility of mounting a platform to the rear of our 26 ft. Jayco travel trailer (not a fifth wheel) for the purpose of carrying a scooter. Thinking of something like a Yamaha Xmax 292 cc with a wet weight of approximately 400 lbs. Knowing that the rear bumper is only good for storing the sewer hose, such a carrier would have to be securely welded to the rectangular tube trailer frame itself. But then with an extra 400 lbs hanging off the rear end I can imagine a potential problem with the sway it might cause. Has anybody ever successfully done this?