[gafftaper]

So you just want the door there... it doesn't have to open right? Instead of braces, you are going to turn the door into a brace. The attached is a quick and not exact sketchup to give you the idea. I'm still learning to use Sketchup. The bottom is a 2X4, the angled piece is just 1x3 (it should reach about 60% of the way up the door.) Go to Home Depot and get one of those 40 or 50 pound cement blocks used in building decks that has the slot cut in it for stringers to fit in. Flip the block over on top of your 2X4 and you've got a very sturdy but portable door.