Cutting up the first sheet of plywood into frame elements went really fast. About 45 minutes, including sweeping up the saw dust and scraps. Here is the result:
Not so successful was my first test of the work platform hoist. Stupid me forgot that that thing is heavy... probably about 80 lbs. That results in about 50-60 lbs of pull in the rope to get the thing off the ground, which is more than I want. Its back to the store this after noon to get a couple more pulleys and some various other hardware to re-rig the hoist with some extra leverage. I figure that I can get the required tension at the human end down to about 20 lbs.