Question [Q] Force-enabling the proximity sensor while the phone is asleep

I use the Gravity Screen app to turn my phone's screen on and off automatically. It works almost perfectly, but I have run into a problem: It seems that the Xperia Arc S disables the proximity sensor automatically when the phone is in deep sleep. This only happens if not connected to a charger though, if I connect the phone, it works perfectly.

My question is: Is it possible to force the phone to keep the proximity sensor on in deep sleep when the phone is running on battery? The app offers several work-arounds, like keeping the cpu awake (not very battery-friendly obviously), or combining the proximity check with a gravity sensor check for the phones position before turning the screen on, but the better solution would be to just enable the sensor.

I have tried creating an empty profile in tasker with the task "stop" and the state set to proximity, then enabled display-off monitoring in Tasker, but sadly this only seems to conflict with Gravity Screen's ability to read the sensor.

This whole thing could possibly also help make pocket mode work more reliably on our phones. I noobishly suspect that this change would have to be made on kernel level?