I have a 2015 Forester 2301 on a Chevy chassis. I'm in the process of putting in a CB radio (it's still on order) and I'm pondering my antenna location choices. I was thinking about mounting it on a bracket at the very end of the driver's side mirror and running the antenna cable through the mirror bracket arm. It won't work, but that's another story.
But, before I decided it wouldn't work I needed to poke around the interior of the cab to determine if there were access points to run the antenna cable from the arm to under the dash. I took off the plastic kickplate on the driver's side and was confronted with a rat's nest of wires and antenna cable. Apparently in their haste to build the units, FR taps into existing wiring with 3M taps and runs power leads off of there. I found one such tap which as it turns out powers the rear/side cameras and the multimedia/nav system. The wire leading from the 3M tap joined two other wires in a crimp on connector cap. The only problem was that the hot wire leading from the 3M tap was holding into the connector by about two strands of the thin copper wire. I corrected that deficiency with a better wire connector so I know it won't come apart. I ended up zip tying everything together into a semblance of order and put the kick plate back on.
The important thing for Chevy owners, and it may apply to Ford owners too, is that if you blow the fuse for the multimedia/nav/camera circuit you won't find it under the hood in the fuse box. There's an inline fuse in the rats nest of wires that FR left for you.
The photos are a bit fuzzy, but you can see the professional wiring done by FR - I already replaced the defective connector. The second photo shows the 3M tap attached to a wire that I don't know goes where. Personally I refuse to use the 3M type taps, I'd rather run a wire to the fuse block and tap into power there. If that tap corrodes it will probably fry whatever's connecting downstream on that green wire. I'm also not sure which antenna cable it is. It's on the driver's side so I don't think it's for the AM/FM radio and the Sirius antenna is on the passenger side too. But there is some type of press fit connection in the antenna line that's buried behind the kickplate. So, if you're having reception problems with a radio or maybe the side/rear cameras, take a look there to make sure the antenna looking cable is connected. You can see it in the bottom center of the first photo.
And - while I was checking the house batteries under the steps leading into the coach I saw light behind the batteries. Upon closer inspection I found a hole about 2 inches in diameter in the back of the step behind the batteries. I'm assuming that it's there to allow for air circulation when the batteries are charging. But, it's a big enough hole that mice, chipmunks (ground squirrels for you westerners), wasps, yellow jackets, black widow spiders, brown recluse spiders and even a snake or two, could easily find a cozy home in your battery compartment. While the mice and chipmunks aren't necessarily dangerous to humans as the other species listed, the do like to chew on wires and can wreak havoc with the connections.
Imagine your surprise when you open your battery compartment - which is inside the coach - and any of the above come flying, crawling or jumping out at you!
To prevent any unwanted passengers I took a piece of screen and mounted it to the outside of the step over the hole. I used caulking and ran a bead around the hole pressing the screen into the caulk. With the screen in place there should be plenty of air circulation, or at least as much as was there before.
Crawl under your steps and take a look at the back of the section where your house batteries are, you'll probably find the same hole.