One of the defects we noticed when we bought our RV is this piece of the aluminum trim strip that became separated from the sidewall. This is a factory defect as when the unit was originally constructed, the trim strip was not properly cut, and over time, the screw holding the strip simply broke off.
To complete this repair, I will be using one of the best adhesive/sealants available, 3M's 5200. This product is designed for the boating industry, and is used for permanent bonds between the fiberglass hull and fittings, underwater thru-hulls, and hull to deck joint. Once bonded with 5200, the bond is permanent, and very difficult - if impossible to remove.
This goop is known as an adhesive/sealant, as it has properties of both.
The 5200 is available in two forms; quick dry (about 24hrs) and standard (48~72 hours). The viscosity of 5200 is medium, so it can run out of vertical joints. For this reason, I probably should have used the faster drying version, but I have had really good luck with the slow cure stuff, so that is what I used.
One word of caution - this stuff is messy, so you should use gloves as well as protection for any surfaces (driveway, etc) that you don't want this stuff permanently bound to. The minimum temperature for bonding is 40deg, but at that temperature, it may take more than 48 hours for the 5200 to cure.
After the application of the 5200, I clamped the trim piece to the sidewall. You can also use a screw or any other method of choice.
As the 5200 is curing, you can wipe off any overburden and clean up with Isopropyl Alcohol. However, once the 5200 has cured, you cannot remove any overburden with alcohol (or a jack-hammer for tha matter).
If you cannot wait 3 days for curing (which means you cannot move the coach), consider using a self-tapping screw rather than a clamp to hold the piece in place as the 5200 cures.
Secret: If you need to remove the items stuck on your RV with 5200, you can use a product called JWB Anti-Bond 2015 that is a spray on chemical that will pulverize 5200. In fact, this product should also work with the lap sealants commonly used with RVs as well.
JWB Anti-Bond is hard to find, and the only place I know where to get it is here.
You can also use JWB Anti-Bond to clean up surface areas of fully cured 5200, but make sure you don't drip it into areas you want to remain bonded. Spray the Anti-Bond on a rag rather than directly on the project, then use the rag to rub off the overburden.