15.5 lbs. of thrust, eh? I've got a Great Planes 1/4 scale Cub (90" span) that turned out to be a lead sled. Flying weight 13+ lbs....flew well with a .61 2-stroke. Sounds like I could scale this thing to fit the props and have everything work out OK. Excess power would be a good thing. I'd say there's a fair-to-middling chance it'd lose more than one engine per flight.

I've used both 2oz and 4oz tanks with reedies...I don't imagine the draw on a Wasp would be much - if any - worse.

Hmm...one problem with having someone go down the line with the ignitor is the push/pull arrangement and the fact that the nacelles are so close together. Be mighty dangerous to do that. Perhaps some sort of wiring harness built in would be a better idea, maybe with a switch or similar to light up only the engine being started.