I think it's worth a try, but I think you're prolly too late. But ... you really aren't gonna know IF you have a problem until you complete the deck. On my Outer Island, I also forgot to put spreaders on my hull after I glassed it. After I completed my deck and started on the seam, I found that my deck was wider than my hull, not the other way around. In my case, the maximum deviation was about 1/4" side/side and 1/8" up/down ... so ... I had to add spreaders inside to hull to push it out.

Ken