I rode a couple of pretty big days at North Beach with my Ross (clothing discount store) found black plastic, single concave shaped like a skim board, but with a slot for fingers and thumb 14" x 10"er. Even have a leash, and all the surfers were riding 8'6" and bigger gun boards.
I'm not really much of a waterman, but them things allow for easy getting out, no fear in the impact zone, and if I took off close to the shoulder, easy wave making.
Now that you remind me, maybe I'll take it to Drakes when I go there. Glassy, clean, offshore wind shorebreak closeouts would be just fine with that and boogie boards.