It's a common issue. Two flimsy J panels are screwed together with no backing in places.
First and best fix is to put backing........even a small 1X2 piece of wood works.
Second and what I end up doing on the road when I see screws backing out, is to just keep using a bigger screw! Jury rigging, I know. But then I forget where they came loose, or forget it happened, and go stupidly on my way for weeks before it happens again and I slap my head........always at a spot where I don't have backing any more!
Speaking of which........I'm going to add a 6 foot 1X2 to my list before next trip May 26, go get it at Lowe's and cut it into small pieces.
I hope I remember.
"Next to prayer, fishing is the most personal relationship of man" Herbert Hoover
"American by Birth, Southern by the Grace of God"Lewis Grizzard
2016 GMC Denali 3500Dually--2017 CC 36CKTS