I'm not in your zone, but last year I had to pick my pumpkins in July as the plants were so wild and ratty looking, they just had to go. I stored the pumpkins on the cooler, shady north side of the house sitting on empty flower pots. I was careful not to let them get wet on the bottom or get any cuts. They lasted past October. Don't know if this would work for you, and don't know about squash.

There is some information if you search "How to Store Pumpkins." Not so sure about the bleach bath.

Nice idea for your wedding, very fun. Best wishes for a wonderful day.