Carry Freedom City sells for $600 in the US, folds flat, no loose parts, includes a sling bag that comes out quickly.
you can strap a suitcase on top of that bag , to the rim of the frame
have the bag as carry on and the frame of trailer and Suitcase as checked pieces.

Wandertec builds a version of the CF Y trailer Here , plywood deck to attach anything to.

They tried to sell them at $600, and they must have sat unsold, did a price cut.
seems like it changes a lot , today : $499, Maybe you can Haggle price over the phone.
to get it back down from there.