On a three trip from Texas up into Missouri in our 2006 Voyage 33V, the front left-side panel (under driver's door and in front of slide unit) came loose from the lower stiffener and flapped while at highway speeds. It actually flexed enough that some tabs on it were outside the storage compartment door.
When I crawled underneath, I found that this stiffener was attached to the panel with what appeared to be double-faced tape or perhaps a mastic.
All I had with me was some silicone sealant and I wasn't sure if this would do the thrice or not. My wife said she had some wide, industrial strength Velcro and asked if I thought it could work. My thought was, "why not?"
So right now the panel is attached to the stiffener with Velcro! So far, so good. I'll know more by the time we get home in another 1,000 miles.
Sometimes you just have to work with what you have.