I was thinking it was being mounted to a vertical surface - hence the suspend/brace comment. It's even easier in your situation to line things up.
You know your boat better than me, but I'd be very wary of putting an inexpensive pie plate on the deck floor. A latching, heavy duty one, sure. But the little pie plates can leak too easily and it's quite possible that in that location it can leak into a cavity (probably with foam) where it might get trapped. What's your access like to the vertical sections inside the CC?
There are much less issues with glue-n-screw on the floor than on a vertical section that isn't as strong. But if you wanted, look into the "Toggler snaptoggle", or similar.
Is your deck cored with wood? I would be really sure to fully saturate the deck holes with resin, which will also provide for longer-lasting "holding power" of the screw.