Are you looking for a sealant or an adhesive? The question sounds like you need an adhesive. A trick I learned from an old contractor is hot glue & Liquid Nails together. Put on the Liquid Nails where needed. Then put on dabs from the hot glue gun. The hot glue will hold instantly (3-6 secs), but will start to release it's bond after 6 months. This gives the Liquid Nails plenty of time to set up permanently. Just get the right Liquid Nails as there are so many to choose from.
"Sometimes I wonder if the world is being run by smart people who are putting us on, or by imbeciles who really mean it." Mark Twain
AIR 22749 WBCCI 2349 NOVA TAC TN-6
1989 345 LE Classic Motorhome