The Burley is the first one that came to my mind. If the case do not fit between the wheels try and build it up with something strong and light like polestyrene.

Next is carry freedom flatbed that is fast to collapse. Maybe you`d need a longer towbar.

About using the glasfiber box of the chello as a trailer base: Look at the BF trailer that is made to be atached to a Samsonlite suitcase. https://www.bikefriday.com/thestore/...oducts_id=8775 Can it be fitted to the chello case instead? If not, could you have longer axels made? Longer towbar? That way it is not really bike+ chello+ trailer that needs to go on the bike, just bike and chello case with wheels, and wheels can be removed. We made such trailers from scratch so I am sure something can be done.