On my I17R, I used the huge Murrays bag that had a tackle system (for a couple of mechanical advantages). I'd tie it to the righting line, fill it up, lift it up with the tackle, and then lean out with it behind me. It weighed a ton and would right the boat instantly. It was overkill for the I17R. I don't know if it would be enough to solo-right a TheMightyHobie18, but it was *really* heavy. Do a test with a friend nearby.

It was harder to retrieve the bag than it was to use the bag: once you are upright it is dragging six feet below your boat.