Karl,
I have the supports left over from our last toyhauler. Took slideout stabilizer/support stands (Photo 1 attached .bmp file) and machined an aluminum disk that's bolted to the top of each. The disks fit into the rubber "snubbers" on your ramp door.
Our last toyhauler had a Carefree of Colorado Add-a-Room on it. They used cable & turnbuckles at a 45 dgree angle for support. You can barely see them in Photo 2. Good idea if your ground is not level; we stayed one place where we backed out over a "ditch" in order to have a nice view in the evening. I never thought the cable was out enough on the door for safe support so we fab'ed the uprights.
Dometic now has the Xtend-a-Room sold at Camping World. It looks as they only use stands for support. (Photo 3)
Dave
Found this photo of 4 cylones headed down the road.