Don't use regular silicone from the hardware store. Buy some ProFlexRV sealant, drill the holes, put some of the ProFlexRV sealant in the hole, then install the screw. It comes in clear, white, offwhite, and brown I believe. I bought and used the clear when I installed my rear view camera. You should be able to find it at RV dealers, and Amazon also sells it. It's about $16 a tube on Amazon, but it's cheap insurance and the right product to use, whereas silicone is not.
2016 Coachmen Freedom Express 282BHDS
2008 Dodge Ram 1500 QC 4x4 Big Horn, 5.7L HEMI