You know.... I actually have something like your describing welded into one of my units. The way the coins are dispensed and the coin return.... was built up then they welded across which would prevent any entry. (That is how my unit is welded.) The welding was for a different reason though.The only thing that would prevent this "hook and yank" scenario would be to weld angle iron around the opening on the inside which would prevent them from being able to hook or grab anything with a tow chain hook.