Thanks for the info everybody.

I'm not too worried about the spray skirt fitting. To eleminate all the hassle of possibly not getting the right size, I think I'll go ahead and send my final cockpit template to www.sealsskirts.com and let them build me a custom one. Seems like you can't go wrong here.

I just cut out the hole a little while ago and it looks pretty good. I located it at least an inch, maybe a little more, aft of what I measured as hopefully the correct CB. Since this is just the recess hole, I could cut the final cockpit cutout even a little further aft if need be, but I think it'll do fine.

Looks like the final dimensions after the coaming is installed will be 16.5" x 31"