Having built kayaks and boats out of many different materials (some that would gag a few of the psuedo kayak purists) this is my opinion. I would avoid voids anywhere in the kayak...including the deck. You can check the edges of the material you are wanting to use and probably come out ok. I also say to be adventurous and do some things you want...the way you want them to be done. I see no problem in pushing the edges of the envelope. Something wonderful may happen. Of course you may end up with a water dog...but that's the chance you have to take. Kayaks are for individualists and many times reflect the personality of the builder (yes...there are some really superior builders). I would also fiberglass the deck. This goes along with the strength and durability factor. Strong is good. Light is good. Strong and light is great. However I think too many people get caught up in the light at all costs circle. If I ever have any doubts I go for the strength. Ok...that's enough. I guess I just woke up wanting to postulate. I like your website. Keep us posted.