Nick Schade recently built a dingy for a customer with a lot of mahogany on the deck...i saw it..absolutely beautiful. Maybe he has pictures here somewhere. But i agree, maybe mahogany isn't the best if your not really good with fitment and finish, and i would'nt do the entire boat with it myself...imo cut a few 2" wide strips for the flatter portions of the deck.
I'd go with 6oz cloth on 3/16" strips and expect the deck to flex a little when you push on it. Carbon fiber underneath on top of the 6oz will stiffen it.

: OK, after having plans for a year and a half to build a Guillemot, I'm
: finally getting ready to start milling wood. (Restoration of a small
: British car got in the way..) I have two 8' long, 30" wide, 2"
: thick mahogany boards that I've thought about using. Due to the increased
: weight of Mahogany vs cedar, could I use 3/16 thick strips and still have
: enough strength? Should I use 6oz cloth or 4oz?
: Any thoughts would be appreciated.