A metal folding-leg sawhorse, a scrap of 3/4 inch plywood, a few bolts from the junk drawer or hardware store, and an hour or so with a jigsaw and a drill for the bolt holes, and you're done. When no longer needed, remove the plywood and you still have yourself a sawhorse.
I do something similar. I have two plastic saw horses that I set up about 5 feet apart. I lay a couple 2x6s down on them and a sheet of plywood on top. A couple clamps on each side, and we’re good to go. I use a shower chair from after I had surgery. Each leg is adjustable enough to not be totally annoyed.
