Pretty much finished (so far.) I still have to find a decent, possibly used, battery monitor, shoot some foam in where I fished the wires clean and re-install the window pillar cover over the wires.
The hardware came early yesterday afternoon. The first thing was to add the 4th panel and connect the wires. The wires from the panels to the controller run about twelve feet. They are 10ga. While I know they could be 9ga strictly speaking and some here will prefer 4ga for everything the controller will only accept 10ga and those panels will only produce 34Amps when perpendicular to the sun on the brightest day of the year on the equator and at a temperature low enough to keep the panel below 75f. I'll be lucky if I get 300w on the best day.
Then 2 holes were drilled in the roof so that they came out in the overhead, front speaker enclosure. I no longer use those speakers but it wouldn't make any difference.
Then the "bitter end" of each wire is fed through into that cabinet space.
The holes were sealed with self leveling Dicor on top and foam sprayed from beneath. A Brick was used to hold the wires down so that they would not stick up into the wind and shake. Once the Dicor sets I will add a blob of it where the wire runs on the roof to keep it in place and remove the brick.
The front pillar cover is removed and the wires fed from the cabinet into the space beneath the cover.
Next the wire is fed into the battery compartment in the front of the RV. It follows the wire harness that you can see going forward. This is a tough feed.
The space is small and filled with a sticky goo, a lot of foam and many other wires. I used a metal fish. I got it years ago for fishing cables in boats and it is great.
Because I needed to fish down because of visibility I pushed the fish through first.
Next I connected some coat-hang-wire which I pulled back. the cables were connected to the coat-hang-wire one at a time and lubricated with pulling wax. Dish soap will work too. Once one was pulled through the process was repeated.
The neighbor's dog Peetie was on hand to offer advice for this part of the job.
The wires were not marked for polarity and I did not think to do that so I checked with a meter. You can see that the meter was reversed and I was making power. Since it read negative on the meter that meant that the lead connected to the - probe was the + wire. I cut them to just a couple of inches longer than they had to be and connected then to the controller. I then connected the 10ga battery cables to the batteries and cut them to length and connected them to the controller.
The holes where the wires went get fire resistant foam since the go through the laughable joke of a firewall. The trim goes back on and we have power.