Need help on Attaching Screws in TV BOX ceiling

I have never seen an RV with less than a 2" thick roof. As long as you keep your screws shorter than that you should have no problem. Finding the actual roof frame itself might require a little trial and error or tapping with a hammer to find the most solid portion of the roof. Look for existing screws that already attach your upper cabinet to the ceiling.
Some coaches, like mine only have an aluminum roof frame so I need sheet metal screws to attach anything.