[millermmail]

Since I didn't get any replies thought I'd post a follow up with what I found over the weekend.

There seems to be a large-ish (about 1 inch x 2-inch) rubber plug below the bracket holding the driver's side of the rear bumper cover on. You can sort-of see it if you remove the brake light housing from above and just barely reach it if you lay on the ground and reach up from below between the tailpipe and bumper-cover straight up.

On the interior there seems to be a hole (but it feels smaller, maybe an inch circle?) that is accessible if you remove the lower and left-side trim, bolt for the rear driver's side tiedown, and driver's side "bag holder clip". It's almost in line with the power socket.

On the other hand, running cables forward from the cargo area was harder. Seems there aren't the usual easy door-trim cable cavities (or I couldn't find them) but rather Subaru runs the cables I could see toward the middle of the car and down into the carpet. I didn't hunt for how to remove the rear seat to get any better location than that, ultimately I just ran my wires over the carpet under a floormat because I needed them to reach the driver's seat well anyways. It still looks a lot better than it did before without wire snaking thru the cargo area visibly.

Since I was working totally by feel I don't have any really good pictures to show it much but I will say it was easier than I expected and didn't require disassembly of the bumper though it would have been FAR easier if I had taken the bumper off. I attached the couple pictures I did get to show what I was doing.

 

[millermmail]

Any reason why you didn't cut the SO-239 off and just solder a new one on once you had the cable run? I would have thought that would be a lot easier than trying to fish that big connector around.

Actually the "kit" that I got (Comet I think it was) the "big" PL-259 connector unscrews and the part you need to fish is only about 1/4 to 3/8 inch, not much bigger than the coax itself. That's how I ultimately got it thru the rubber plug while keeping a tight seal around the coax in the end. I just didn't take any pics of it that way. It was a cool design, I didn't realize that when I bought it.
COMET-NCG 3D5M Antenna Accessories Mobile, 3D5M

I too would like to know the best way. I want to put a light bar on the rear of a roof cage facing backwards and would like to bring it into the cabin otherwise i would be running it underneath the length of the car all the way to the battery. Next time I clean my car ill take a pretty serious look. I don't know if this will help you but i think there is a spot underneath the bumper that goes into the spare tire area, i was thinking about running my trailer wiring through that spot.

There's certainly plugs under the spare tire well - that's where all the trailer wiring is supposed to come thru (afaik all models anyway). That would work but you'd have some doubling back, the plus side would be its easier to get at. The plug I found on mine would probably be very obvious if you took the bumper cover off but was doable with it on. I don't know if it exists on any other model years besides 2012 but it is nifty that it pops out right by the power port and wiring stuff and can go easily up the outside of the seal and pop out the hatch hinge near the luggage rail with ease.

I found a pic of someone else's "hitch install OEM method" guide and you can just see the plug I went thru on my car. Look below the driver's tail light wiring there's a large white bracket. Immediately below that white bracket (partly hidden by it) is a black rubber oval. That passes into the body of the cargo area. If you click on his picture you can zoom in and see it better.
https://digitalnigel.com/wordpress/wp-content/uploads/2012/06/IMG_2535.jpg
https://digitalnigel.com/wordpress/?p=1179