If water infiltrated, it could possibly be pooling at the bottom of the cab-over area, and rot could have started. If the framing is rotting, there won't be anything substantial to screw into.
The inlaws' motorhome had water seep in the cab-over. No one noticed until I was cleaning it for them and wondered why the flies were flipping about up there. Took the mattress off and my knee pressed into the soft 'floor'. We fixed it - the entire floor area was water damaged and the side wall areas up for about 6" were blackened too.