Cracked SUP Handle

I'm fixing a buddy's (Jimmy) SUP board.  Some water keeps seeping out of the handle area.  Jimmy said it might be the old deck pad, but I kept the board out in the sun at my house to see if I could get more water to come out.  There were salt deposits all along the handle area.

Originally I was going to just lay down a cap sheet with laps over the edge, but with the coverage required, the short space to work in, and the fact that the handle opens inward, I couldn't get the laps to stay down.

I shifted over to using milled fibers to get a slurry.  I had to stay with the board though to make sure the slurry didn't slump back into the box.  Times like this I wish I had fast curing resin.

Today I'll grind down the overage with the grinder, then use the dremmel to trim the inside portions.