well it looks like this thread choked on it's own vomit and died, so I went and made my own stand using scrap bits and pieces and my own fertile imagination.
I did have to buy some castors with brakes, but I went to a specialist shop so they were fairly cheap compared to hardware store prices. The tray is just an old Dexion shelf with the lip crimped over so doodads couldn't hide under there.
The threaded studs hanging down under the platform are used with along pieces of angle (with holes at either end) to bolt through the footpegs.
I can put a bare frame on this with either forks/wheel at one end, or swingarm/wheel at the other, and it won't tip over.