I Like the Rob English bottom bracket idea. I am thinking we could adopt that. Just don't have an idea yet how the bottom bracket shell swivels.
It seems like a two piece chainstay (l/r) with a pinch clamp at the front right chainstay and a bridge anchoring the two pieces at the seat tube area... guessing extra bearings and an axle of some sort through the shell, with bb carried in the chainstays.. seatstay has pivots at the dropout so the seatstay can fold flat .. looks slick .. but I'm just hazarding a guess from pictures ..