I built a Yare in '95 from The Kayak Shop. At that time it was specified to use 3 mm okoume on the deck, with glass and tape only at the seams. I believe the book said it was OK but unnecessary to glass over the top, so I didn't. My kids took great delight in wet reentry practice, and I did some too. Having no deck beams aft of the cockpit, and no glass inside or out, it oilcanned badly. In year 3 it finally popped seams on both sides, and I had to redeck it.

The second time around I used 4 mm (I believe that is recomended now over the 3 mm by CLC), glassed inside and out (4 oz.), and it's hell for stout. Probably overkill, but I took no chances after the first experience.

So, IMO you are doing the right thing. The worst that can happen is a little more time under construction and a little extra weight, but those are a small price to pay for peace of mind.