Thru Hull (transom) repair ?

[BigLew]

I'd build a plud and scarf it in.

Start with a 2-2 1/4" forstner bit thru a guide of 1/2" ply. Drill out a shallow (3/8-1/2) on both sides and then bore out the original hole to good wood. Make a plug laminated like you would do a transom and then set that in place and use the over-drill collars areas to finish it off both inside and out.

If you will be replacing the thru hull, be sure to line the hole with resin,thus sealing the wood core. Then replace the thru hull.
If you plan it out, step by step, and gather the needed materials ahead of time, it take a day or probably less. Just my 2 cents.

Good luck!