Hope this helps some as well. I've got a 2003 Jayco qwest 8u. I bought it last year and found out the previous owner just left it out all the time. All the vinyl seam strips were brittle and all the butyl tape was hard as a rock. In the process of redoing all that I noticed he had used silicon for a lot of touch ups and yet still suffered a lot of water damage. After a ton of looking online I used. Dicor Lap Non Leveling Sealant (
https://dicorproducts.com/product/no...-lap-sealants/)
It's not cheap around 13.00/tube last i bought it off ebay. Comes out thick and dries quick.. But it seals it. Definitely would recommend. Just my .02 i'm sure others have their go to as well, but it's done nice for me.