And the answer is:
1 and 1/4" stainless bolts with a flat head, 7/16 stainless nuts and regular steel flat washers. Two of the legs were accessible by removing ventilation hoods, on the back edge of the transom. Another leg could be gotten to by sliding into the rear berth. There was a precut hole in the inner lining, giving access to the nuts.
The last leg was accessible thru the cockpit storage locker. Was able to get all the nuts off except one.
The storage locker leg had 1 bolt where the slot was not square. Could not hold backup to get the nut off since the nut on that particular bolt was stuck. Could not grab the bolt top with a vise grip either. Probably going back tomorrow and cut the bolt head with a dremel to get it off.
Did take the boat out for a couple hours but the wind direction and speed led to a lot of unpleasant hobby horsing. There was enough bouncing to make the drawers fall/pop out of the cabinetry and hit the deck.
Tangled the furler rope when replacing it so when I tried to pull out that sail, it got hung up.
Main halyard also got stuck 1/2 way up. Had to drop main, untangle it, and go up again.