Here's what I ended up with - PaulF's rack cannibalised for the plastic parts, with new aluminium rods:
I've got a C bag as well, which is very good but, as in Kim's review, large - great for carrying a lot, but bulky if you're just carrying a few things. Based on an
idea from Instructables.
I do wonder about carrying things on the back. The limitations are obvious, including the need to use the platform as the base for the folded machine, and heel clearance. However, something like a luggage block on the side of the rack maybe? Bit beyond my fabrication skills though.