what I did on my 32
Was to locate the exact location of the stanchion inside and took a 2" hole saw and drilled the cabin liner out with two holes side by side so I could access the nuts and get a backing plate inside, getting to the nuts with wrench's,sockets and custom bent tools didn't work on all of them so what did work like a charm was a Craftsman flex head racheting box wrench's (I use them all the time now)To cover the holes I found some plastic that match's the liner pretty close to color and made 3X5 covers and screwed them over the holes.BTW I installed standard 1/4 nuts cause I was able to spin them on pretty easy with my finger then after the caulking dried a couple days later I snugged them up tight and then installed nylock nuts over them.