We cut our leg off flush with the rib. The plug is held to the leg with a couple of screws. The plug extends out of the leg about the same length as what's left in the bilge. It's quite sturdy.
Only thing to be concerned about is that the cut leg has not been cut too short. If so, rather than try to make a more complex plug, just put a piece of wood up inside the hole in the table to compensate for length.