flexible solar panel

Solar cells are fabricated on crystalline silicon wafers. That is a brittle material. Some of the marketing videos show a guy folding a cell. That works (once) because the cell is very thin. But ask him what happens when you apply constant bending stress to those cells or flex those cells multiple times. Microcracks will ultimately propagate across the cell and it will fracture, often opening the entire cell circuit, which is in series.  The result is a dead module. 

The polymer superstrate used on the "flexible" modules is not nearly as robust and the glass superstrate used on conventional modules. It will degrade, discolor, hold dirt, and is prone to cupping. Then there is the risk of hail damage. The result is a dead or low performing module. 

The "flexible" modules are intended to be attached directly to a roof or other rigid surface. By not providing back side cooling these modules will run hot, reducing performance and further reducing product life. Much better to use conventional modules in a stand off mounting configuration that allows some airflow to cool the backside, and keeps the trailer cooler as well.

Cells in modules are in series, and the current generated by them is proportional to the irradiance they receive, so if the intent is to attach the "flexible" modules to a curved surface like the front part of an rPod, there will be a significant performance degradation because the cells won't all be receiving the same irradiance levels. 

Attaching with pressure sensitive tape, like VHB tape, requires great care, and a perfectly clean and totally dry surfaces to be secure. And it requires pressure to be applied to activate the adhesive. That means you are pressing hard on the brittle solar cells.

The manufacturers know all this of course, so typical manufacturer's warranties on conventional glass modules are 25-30 years. "Flexible" ones are 1 or 2 years typically. 

So, if you won't be frustrated if you have to replace your modules every few years at best, and weight is critically important, then "flexible" might be the way to go, but be sure you have a way in mind to remove them from whatever they're attached to without causing damage so you can replace them.

If not then stick with conventional glass superstrate modules, I'm certain you'll be a lot happier in the long run. There are several ways to mount conventional glass solar modules on a trailer without putting holes in the roof. See the current thread "Any Upgrade the Solar in a 190" for one of them.

Re the charge controller location you could place that under the shower in the 179 and connect it at the 12V fuse buss in the power center.  As GlueGuy says there is no need to use the Zamp wires. 

I'm not too excited about the idea of running the conductors through the shower vent.  You could use one of these. It is not a mechanical connection so there isn't any physical stress on it, so there shouldn't be much risk of it leaking. I plan to remove my TV antenna which I never use and use that as the chase for my solar installation.