I agree with you about avoiding bolts through the deckif possible.
With our Rib we didn't need any chocks and simply lashed the dink to the deck using lines through our stanchion bases pulled tight so the dink was "compressed".
This got me thinking about your situation and I wonder if you could contruct something that had a comressible rubberized "bottom" for use as a chock. I'm thinking of something like those inflatable seat "tubes" you often see on inflatable dinks. then you could lash your dink on top of a couple of those which would stow nicely deflated? Might work ok.