Does the cockpit drain through the outboard well, if so add a way to drain the cockpit as part of the infill.
Look around the yard and dumpsters for a piece of scrap marine plywood, old bulkhead, bits of cabinets,... to fill hole from inside with plywood patch and fiberglass. Then fill and fair exterior.
Make sure to reinforce the transom area for the outboard bracket. Adding a cable remote for outboard control would also be a good idea.
Filling the hole and lifting the outboard prop out of the water may give you with less drag an extra knot under sail.
Look around the yard and dumpsters for a piece of scrap marine plywood, old bulkhead, bits of cabinets,... to fill hole from inside with plywood patch and fiberglass. Then fill and fair exterior.
Make sure to reinforce the transom area for the outboard bracket. Adding a cable remote for outboard control would also be a good idea.
Filling the hole and lifting the outboard prop out of the water may give you with less drag an extra knot under sail.