Been there done that. That’s a lot of work, and can be a pain in the ass. Thanks for posting it for everyone.
The reverse solenoid pictured is great for all the flat land states, but in CA there is another one preferred that blocks the pressure and then also bleeds any residual pressure from the calipers back into the reservoir.
REVERSING SOLENOID VALVES
This is very helpful if you are facing down hill, and need to back up since the weight of the trailer will be enough to pressurize the system before you pop it in reverse. I know this first hand…