I don't know how your port could be so far away from the transom, there isn't that much hull behind the crossbar, but I'll take your word for it.

Matt is right, you need a port that's close enough to allow you to use longer bolts, to connect to nuts on the inside.

You also need to be careful to be sure the fiberglass core hasn't turned to mush from the water intrusion. You may be in for a big job, and something that might be better left to a professional.

You might also check with a local fleet, maybe someone close to you has done this, or can refer you to a good shop.

Good luck.

Mike