That's super awesome, I'm really diggin' it!
"Quick Disconnect are normal Mt Bike seat clamps ( ebay $4 each ) with 3/8" OD to 1/4" ID bushings from Lowes ....."
That's a handy tip, to be sure. I sold my sedan brace and got the Whiteline version only because it had the disconnects. It didn't even occur to me to try seat clamps.
BTW... Wagons, FTW!