That's a subject for a pro hull builder but I'll add my half cent wheat copper.
I've seen a few and one with part of a carbon prop blade embedded in it. Carbon cuts glass like butter especially at speed but getting off subject.
Yeah, it's better to replace the stringer entirely and re-glass if your able? Sounds like it's a question of your options to your health and all around you if a patch fails?
New glass hulls are what now, high 3's and your debating a potential fix vs massive medical bills over a new hull? Assuming your asking for fiberglass advice to a mount stringer?
A half cent wheat penny is worth more now than when it was stamped but it won't float either!
If your opted to skag a stinger along side, please put something on this hull to notify others of "home built junk beware"