For whatever it's worth, we have a very similar trailer to yours, and we love our 120 watt portable -- it tops up the batteries almost every day. Point it south and leave it there.
Wind is a concern, but we put big rocks into the support struts. After many years of use, no problems.
By the way, our panel is a no-name knock-off of the Renogy. We got lucky -- the panel is great -- but if you want to be sure of high quality, buy a name brand.
If you boondock in heavy shade (which we do), you may want an extra long power cable. Use thick wire -- like 10 gauge -- to avoid voltage drop. Our cable is 50 feet long -- so the trailer is in the shade and the panel is in the sun.
If you are in really deep shade, and you have a spare battery, put the panel and the battery out in a sunny patch, away from your trailer. We've had to do that once or twice a year.
After the spare is charged, just swap out your depleted battery.