Are you saying you don't have any hatches cut out to access the interior?

I'd start with the plan to cut at least an inch off the ends so the ends of the kayak aren't as sharp as spear. Do this after the end pours are in. Of course this kind of depends on how far from the ends you've already put the grab loop holes.

With the grab loop holes covered,kayak end down on an angle and sideways do two small pours in . Reaching in through the hatch hole pour a couple oz down one sheer seam it'll settle at an angle over the first hole. When it hardens turn the kayak over and do the other side. For the side that has a leak but the grab loop hole goes through epoxy just cut, round over, seal and glass.