I believe Proflex is used on vertical surfaces and Dicor Lap Sealant is used on the horizontals, like the roof. Dicor self levels. I used clear Proflex and white Dicor.
If I could be brave enough to suggest something. changing the Thread’s heading to something like this: “general maintenance suggestions for a five year old trailer” would be very helpful for other forum members. A change to the heading may get more answers and in the future we can search for it under a heading like “general maintenance.”
I write this as someone who can spend lots of time doing forum searches.
Anyway it looks like you are getting great suggestions. Have fun full timing