Do the transom from the inside, I have seen it done both ways and from the inside is by far the best, especially since you will have it gutted anyway. Fully sealed pods have an inspection plate in the top to access the engine bolts. When I did my boat I got all my supplies from FGI? I think was the place, I will see if I can dig up the name, buying rolls of mat is not that expensive, and resin in drums is not cheap, but OK.