RE: PVC Pipe boxstand??
Sounds like a great idea. Here's a suggestion. If your terrain is anything like where I live, you will have a hard time finding a level spot to put it. So, whatever size pvc you decide on for the legs, get some 3' or so lengths of the next size larger to sleeve over the legs. Drill some holes through all the way through them at 1" to 2" intervals and insert a pin so you can adjust the leg length to fit the terrain.
Personally though, I'd just build the box, camo it up real good, and let it sit on the ground. No need for a floor. A lot easier to set up and not as much to haul in to your location. Should still give you a good hide. Of course, maybe you need the height to have a good view of your hunting area.
Anyway, good luck, and I want to see a picture of the finished product also.