Permanent deck plate.
Ed and others, Sometimes the cheapest long term is the most expensive. I've always maintained that the most expensive widget is often the best or at least what works best for a given project which allows me to buy it just once. Do consider buying a stainless steel or bronze deck plate to fill that hole, it'll be the last one you ever buy and won't yellow, crack or look cheap over time. My two cents worth that I borrowed from Loren, Glyn Judson, E31 hull #55, Marina del Rey CA