I believe the only area it is supposed to touch is in the horseshoe, cutout area.
My 1999 Class C, has water damage in the overhead and is drooping. The OSB wood?, is coming apart under the cloth covering. I have removed the sliding bunk wood, that was crumbling and sealed the leak ( I think ).
My next step is to pull up the wood and figure out what to support and replace it with.
I'm thinking, PVC lumber or treated plywood and some aluminum 1X1 square tube, for supports.
Until you can pull it apart, you could slip a closed cell foam pad, in there, to stop the banging.
There are some posts on this site, about rebuilding that area.