I would respectfully caution anyone about glueing a flex panel to the roof of the trailer. There are a number of reasons not to do this.
Firstly, the lack of ventilation under the panel can precipitate several problems; the surface of the panels will heat up more readily, and this will result in reduced performance. All solar panels function better and more efficiently at cooler temperatures. Flex panels are no different.
Second: Unless your panel is highly engineered with top-end materials, the excessive heat can promote delamination, melting and broken circuits. This has been a problem with most first gen flex panels, and will continue to be a problem with current lower quality flex panels. Quality panels engineered for the rigors of a marine environment, and applied to boat surfaces (as opposed to those sold by RV suppliers or Amazon) are probably the best for a surface-mount application on a trailer. But even here, that market and product is a hard one to access and assess.
Thirdly, when your panel stops working (and at some point it will... maybe sooner than you expected) you will have a dickens of a time removing it.
Fourthly, panels require full sun and no shadows. Otherwise their performance is reduced drastically, or entirely. Now you must park your trailer in full sun, if it is even possible, in order for the panel to work at all. Parking in the shade is usually more desirable, and in many locations is the only option available.
Fifthly and lastly, you are unable to locate the panel away from the trailer in full sun, or set at an angle to optimize efficiency.
All of these problems (and several more) are discussed with varying comprehensiveness on this site:
7 Major Problems with Flexible Solar Panels and Their Solutions , among other cautionary sites.
Having said all that, I
did install install a flex panel on the roof of the 560, with ventilation underneath and the ability to secure it from theft, and position it away from the trailer for efficiency. The major offsetting factors, against all of the negative ones above, was that it was lightweight, manageable, and stowable. As compared to a glass unit.
Was it worth the cost and effort? The jury is still out. I have needed to use the panel very little to date as most of our travel has been eastern, and in the fall, at established campgrounds with electrical service. But I do anticipate that it will come in very handy in the West/Southwest, boondocking, or in non-serviced sites in the future, as we become more adventurous with the trailer and our travel destinations. We'll see.