I saw your thread on that, I don't know if we can help. Ours is a pusher with a hundred gal tank, we couldn't see some of the nuts but there was just enough room to feel for them. A couple places there were not nuts and bolts more like the bolts had a piont and no nut.
The hardest part was sitting up to get an angel to reach up there, that's why she was under I'm 6'4" and just couldn't get my big frame in some spots