I'm not sure where you get them (possibly tent supplies, I don't camp, but I think they make pop-up tents that use encased collapsible poles), but I have a collapsible sail (Windpaddle) for my kayaks that uses some kind of composite for the batten (fiberglass?) that folds pretty extensively into a much smaller circle (48 cm from 132 cm when deployed). If you could get a couple pieces of that rod, you could make a twin tube top tube like your earlier pictures with them and they should be able to fold with the frame. Of course, where you get it and how you anchor it . . .
Somewhat related to the theme, my recently departed grandfather supplemented his iceman income during the US Prohibition with the time-honored entrepreneurial tradition of manufacturing and selling illegal booze. Not quite a bootlegger (though his Packard limo could probably have outrun a few revenuers), but along the lines.