You oughta try one of those shut off doors they sell and report back to us how they do. 'Can't remember the name of them, but somebody on here's bound to remember.
Looking back at your picture - you've got it timed to drop with a mechanism, right? If you made it in the daylight hours, maybe it'd decrease the 'coons' bravery.
...and have dominion over the fish of the sea, and over the fowl of the air, and over every living thing that moveth upon the earth. Gen. 1:28
Wanting deer to get it when they want it or just happen upon it, most of us just free flow it. It costs more, but it gets to where we want it to get.
This one here does not feed protein during the season because at that time, we don't want deer to get the feed on their timeline, but ours. That time is when the corn feeders go off.