Legend 37 deck fill

[geek_guy]

I have a 87 Legend 37. The deck fills need new seals. I did the forward water yesterday. All fine there. I then checked the one in the head starboard. It's in desperate need as well. But there is a fiberglass cover that starts about mid cabin, and goes nearly to the outside, and covers the below deck portion of the thru hull, and hose.

How do you get to the underside of the fill to rebed?

Thanks.

Dave