How about a manual on/off valve installed on the gear down pressure line? With the valve closed, you can assemble the plane, pressurize the system, turn on the radio, insure gear doors are open before opening the valve and dropping the gear. Then just leave the valve open for flying. I've seen a similar fix for the airplanes with this valve and retracts that need pressure to keep the gear down and locked. When you power down the system the pressure is released and the gear becomes unlocked and the airplane ends up on its belly, so a valve is installed that you shut off before powering down the system that holds the pressure.

KennyMac