I had a similar issue this past spring. I noticed there was a large amount of some kind of caulking behind the mirror but it is also held by mirror clips. I tried construction adhesive with minimal results, though the metal clips hold everything tight, but I would really like to find the "correct" product.
After an internet search, I see that Liquid Nails makes a mirror adhesive, LN-930, which comes in 10 ounce tubes for about $5 at Home Depot. Palmer Mirro-Mastic sells for $7 at Amazon.com. I think I will buy one of these and re-install. I'll feel better knowing it is installed as per the original. Thanks for the help.
2006 Safari 28' SE (Sylvia) 75th Anniversary Edition
2010 Toyota Tundra 4x4