Started Reverse Camera install

Putting in a Natika reverse camera with the caveat that I am adding a toggle on the dash connected to acc power (via a fuse) that runs to the camera along with the typical power coming from the reverse light. The reverse light power is connected to the camera power plus the acc power via a diode so that when I use the camera while driving, say, the reverse light does not come on as well. That might scare the life out of a driver behind me. Anywho, I drilled a hole in the tailgate hatch as seen here:


My question follows. I ran the wiring under the truck along with the other factory wiring and entered the cab via a hole where other wiring goes in right underneath the driver side seat area. I had to poke a hole aloneside the other wiring. How would you seal this up?


BTW: a crappy diagram is here. (Yes the diode notation usually has a line to the right of the vertex. It was late...)

 

Silicone both sides. Call it a day.