I used 3M5200 to attach brackets for a panel on the roof of a Casita. The panel never flew off when I owned it.
The problem I see with the 5200 stuff is that if you ever wanted or needed to change something that stuff is permanent! With an aluminum roof skin, removing a bracket might end up removing a piece of the roof skin. There are so many good sealants I would rather see someone use a combination of stainless bolt, nut and washers and sealants. Panels do fail occasionally and an exact replacement may not be available. You can always plug an old hole with sealant and move the mount to a new location. Most pop up have holes holding racks, vents and other gear but folks are so against more holes. Even folks with thick fiberglass roofs like on Casitas and Escapes vibrate when you suggest drilling a hole and using a bolt.