I added solar to our Phoenix Cruiser a few years ago and love it. First, I put 100 watt Renogy panel from Amazon on the roof using a mounting kit. It was hard finding the ribs and to make sure I used Dicor on the mounting kit where it met the roof to help glue it down. Next season, I added another 100 watt but I used a flexible solar panel and attached it with 3M industrial mounting tape (same as used to attach car exterior mirrors). The next year, I added another 100 watt panel but this time I built a frame for it and use fifty feet of cord to move it around so I can put it in the sun if I am camped in the shade. That works great and really gooses the system.
I used a simple Renogy controller that came in a kit with the first panel I installed and simply hooked the next two panels into the wiring going to it. I made a plug for the portable panel so I can unplug it and carry it in the toad when moving around.
We often boondock for a couple of weeks at a time and find this system keeps our batteries well charged. We have two 6v lead acid golf cart batteries for the coach. Even with the two hundred watts on the roof, we will get some pretty surprising amounts of charging on a cloudy day or under broken shade.
If I were doing it again, I would buy three flexible panels. They only weigh 7 pounds as I recall. The 3M tape is amazing and you can put Dicor around the edge of those panels if you so desire for safety. I check the panels and the roof in general pretty often and have never had a problem. Now, some folks say the flex panels are inferior but mine measures the same output as the rigid panel. The panels cost about $150 each on Amazon, the controller was less than $30 and the wire was ????
As to routing...........that would vary from rig to rig but the vent mentioned is a common solution from what I have read. Solar isn't rocket science, just a panel or two, some wire, a controller and hook it all up. I did a very simple system and it meets my needs. By the way, I also bought a digital voltmeter on Amazon with a nice large read out of volts and I hooked that into the system so I can monitor the batteries, the controller etc.
PSW
2013 Phoenix Cruiser 2350
2014 Jeep Cherokee behind it
and a 2007 Roadtrek 210P for touring