A couple things come to mind in viewing the pic of trailer and motorcycle loaded. FW trailers of your size have a lot of movement vertically at the rear end while being towed, especially across bridges and road construction areas. It would appear that all suspension for the swivel trailer is in the wheel assembly. If I attached a swivel trailer like yours I would not load it down with an expensive motorcycle until I was certain it was safe. Seems that the trailer could become a "springboard" for launching the motorcycle no matter how secure the tie downs were.
From a swivel trailer web sight:
https://www.cruiserlifts.com/collect...ndem-tow-dolly
https://www.cruiserlifts.com/collect...8-single-wheel
"There are basically 22 states that do not allow double towing, some of them call it triple towing. We consider the system an extension of the Fifth wheel or motor home. (Not a Trailer).
Although we do not agree, The State of New York has decided to reclass our swivelwheel system therefore, it could fall under the double/triple towing law."
Here's proof it can be done.
https://www.cruiserlifts.com/collect...8-single-wheel