you are the guy on the spot and will know best what clearances you have etc

this is what i would do....

probably best to leave the cutting of another port as a last resort/winter job if a repair from inside the well doesn't fix the leak

until it gets some fiberglass cloth covering the area, either front or back, it is going to be weaker, so if you are only going to seal the leak, and not get cloth in there, you'll want to make sure that board is either in or out from now on

the next step will depend on how much space you have inside the well

i still think taking the hull off and putting it vertically against a tree or building is going to be your best bet, working with gravity is so much easier than trying to fight it. but if you do that you'll probably need to work from a high ladder and leaning on those can be dangerous...

to try and find out how much space you have between the sliding dagger and damaged area of the well what about trying to cut up and old sheet and sticking in some cotton patches with a water based glue. just as a trial run and to see how many you can get in before the dagger starts dragging them out. if you can get a few layers in, and the board still has clearance, you probably have enough space for a layer of glass cloth

if so, use some cheap long artist brushes to get the resin in there, to wet the area out, and drop a patch on top and then wet out the rest of the cloth

be as clean as possible and as suggested have some dowel with cotton cloth taped on the ends to wipe off any resin that drips where you don't want it. get rid of it before it sets as the last thing you want is a binding board that you have to hammer down and stress the repair

if you find you have no clearance for cloth just go for thickened epoxy CAREFULLY worked into the cracks with brushes and sticks

if you have some 80grit paper wrapped around a dowel you should be able to clean it up reasonably between when the resin kicks and before it goes rock hard