Use a tie down . wrap it around the flywheel , hook to itself and the other end to a solid part of the frame . wrench on the nut slowly until the tie down get tight on itself .
Hold it there and then apply power to remove the nut .
As for using a piston stop , I've never in my life even heard of any of the destruction you worry about .
Just stuff a length of rope into the combustion chamber as it approaches TDC .