The plans say to cut 4 pieces from 9mm ply, that would be a height of 18mm... seems like too much. Also, not liking the idea of having to buy a piece of 9mm just for the cockpit spacer.
looking at two layers of 4mm and I'm thinking that might be good enough, perhaps 3 layers. Wondering what comes in the kit and what other plans builders are doing.
P.S. thanks for everyone's help thus far, just glassed the deck and REALLY happy with the progress to date :-D