Since this is something i have thought a lot about on my 40/40, i have one last option for your consideration. Do you have genoa tracks and a larger headsail ? On my 40/40 i have only been using my self tacking jib, but i could take that down, lash the jjib sheet to the toe rail and rig up my larger sail with the sheets led to the combing winches. That would free up the foredeck to place my rib upside down.
This works best if you are taking the Bermuda and then straight down route where you will most likely be reaching the whole way. I wouldn’t do this if i was to do a lot of hop skip and jumps along the coast where id be anchoring often.
I still think that storing it upside down and lashed firmly (tied to your stern deck cleats is the best way. The pushpit rails will never prevent flexing no matter how tightly you tie it down.