Looking for opinions for which sealant to use for RV outdoor light replacement & cargo door/frame replacement.
Silicone, caulk, rubber, plastic? Which brands have proven best?

Thanks in advance.

Just so other Keystone owners know, I called Keystone & they told me to use clear silicone on the compartment, light & side areas.  There are special sealants for the roof which we didn't get into.

I use GE Clear Silicone for stuff like that. I like it because it comes in a squeeze tube instead of just one that goes into a caulking gun and the remainder you don't use doesn't dry out. Pretty much any brand will do for what you're looking for though…silicone is pretty much silicone.

Since we have a four color painted RV, we are using a “clear” caulk on all portions of the coach that are painted (i.e., the sides). The specific caulk we are using is Geocel’s Pro Flex Crystal Clear RV Flexible Sealant -- I am very happy with that product. I initially learned about that caulk by reading various caulk related threads on different RV forums. RVs that are predominately white, or another solid color, likely have more options (e.g., Dicor). For the roof, we use Dicor.

Silicone based caulks will also work, but we decided against using silicone due to some friend's experiences and reading similar comments on various blogs and forums (i.e., the silicone caulk deteriorated relatively quickly and you need to fully remove the old silicone caulk prior to reapplication, because the old and new silicone caulk will not stick to each other).

We have been happy with our caulk choices.