This looks like a nice and simple idea. Some states require an emergency/parking brake that is manual, and not hydraulic though. That would be the only issue people might run into. You could probably even plumb it into the line running in the tunnel, and then drill a hole for the button on the tunnel cap.Anyone have experience with a simple park lock style device?
For example: https://www.speedwaymotors.com/Speedway-Park-Lok-Universal-Hydraulic-Parking-Brake-Line-Lock,1970.html
I won't be required to have a separate system, seems like I could just go this route for a parking brake (manual transmission). While holding the brakes, push the button. It'll hold the pressure till the brake pedal is pushed again. Not quite as useful as a solenoid based line lock to throw on the front but simple concept for a parking brake.