What was I thinking???

I have a 2012 ACSB with a stock stereo system. I decided I "needed" a new stereo. I wanted something with Bluetooth, Android Auto, and a Backup Camera. I opted to get a JVC KM750BT, not the top of the line, but certainly an upgrade from what I had. Over the years I have installed a half dozen or so stereos into cars I have previously owned. The install on the stereo was not overly difficult. I used butt connectors to connect all the wires and insalled the HU. It was working well, now is the time to install the backup camera. I was not happy having used the butt connectors and since I had to remove the HU to hook up the camera, I pulled the wiring harness from the stereo, cut off the butt connctors and soldered all the connections and enclosed each one in shrink tube. A much preferrred method of connecting wires.
I attached the camera to the license plate, put the wire in a split loom and attached it to the frame and ran it to the engine compartment. It was at this point I realized I was way past my prime to be crawling around under my truck for this job. There was a grommet on the passenger behind the cabin air filter and I got it into the cab, but the wire is about three feet too short. The firewall on these trucks are tighter than a frog's butt.
Where do you get this wire through the wall to get it to reac the HU.
Any help or suggestions would be appreciated
THNX

 

There’s typically a grommet under the driver and passenger seats. Pop off the door sill and lift up the carpet and follow the factory wiring. If you run it through there instead of all the way up to the firewall, you’ll be left with about a foot of slack behind the radio which the perfect length

 

I dont have to remove the seat, do I?

 

I never do. Normally it’s an inch or two past the carpet line. Take a peek and see.

 

Thnx, I appreciate it. Meant to thank you in my first reply, but the mind is one of the first things to go, I Think

 

Thnx, I really appreciate that. I meant to thank you in my first reply, but the mind is the first thing to go , I think.

 

Certainly looks that way!