nasty

what about taking the hull off, leaning/tying it against a tree, getting on a ladder and dripping some thickened epoxy into the crack off a bit of dowel

if possible put some duct tape on the inside of the crack to prevent too much drip through by reaching through the port

could also use 5 minute araldite too prevent too much dripping through if you can't get backing tape on

depending on access and clearance after that you could clean up the set epoxy with sandpaper on sticks and then put a single layer of cloth on. (both sides???)