Have you checked the folding trailer and 'trailer in a bag' options? They don't take much storage space, especially the 'trailer in a bag', which you can literally take it apart and put it away in a duffle bag.
Stinger make both. They are much more expensive though, and only allow you to carry one motorcycle, nothing else.
https://www.stingertrailer.com/produ...iler-in-a-bag/
https://www.stingertrailer.com/produ...lding-trailer/