I likely wont be able to follow up soon, but..
My uunitsholdingvoltage isn't much lower than what it takes to drop the gate. The thing relies heavily on balance.
This trick is how pinball flippers used to work. High volt except at the very end of the stroke. It helps keep a coil cool as possible.
A timed drop or cut off would work.
I think my gate is on a 12vac doorbell transformer. I took the time to test for heat and so feel safe parked there. 
1min, 3min, 8min, 15min, 30min, 1hr, 2hr, 4hr, etc
Pressure switches are kinda my go to.(Older are better imo. Better leaves/points) Isolated rail is fine mostly, but sometimes a traction tire Loco or lighted/powered car may object to loosing the one outer rail's connection. A minor concern really.
Isolation in curves; isolating the inside rail seems to have less impact on rolling stock operation to me.
A thermal disconnect is a good idea too. Note your coffee makers warming plate uses at least two inline thermal devices. One regulates "normal temp" trips off at X° and resets upon cooling below that. The other is a higher temperature device; a "fuse" that doesn't reset once temp. is maxed. This latter prevents disaster should the first unit fail stuck closed (on)
