Hey wise... I'm intrigued by your oven thingy... let me see if I got it right. You take 2 garbage can lids. To one, you add 3 tabs that stick out from the lip. I'm guessing that you'd pop rivet or bolt on some little strips of aluminum or steel strapping or something. (?) These things keep the lips of the 2 lids together when you make a clam-shell out 'em. Then you put a pizza pan or something like that inside and bake away like it was a dutch oven. Does the pan just sit on the bottom inside, or do you use some spacer to keep it off the bottom? You said legs are nice but not needed. I'm guessin' the best ones would be really short stubby ones, so that it still sits on the coals (?) Have you ever tried adding a little BBQ thermometer to the lid? I'd imagine that should work to keep the guesswork out of the number of coals.
Have you ever tried baking pizza in 'em?
We're going on a camping trip with some families in June, and I'm sure I'd make a big impression if I could make "garbage can pizza"

My friend bought a fancy $200 coleman folding grill last fall and is dying to try it out (and impress us) with it on this trip. I think me cooking in a couple garbage can lids would trump him big time.