I have similar feeder and built a bigger "awning" over the food thrower. It helped in light soakings, but when we got a good rain, I was messing with it for a couple of days. Another note, depending were you install it, these feeders on the beginning and end of the cycle "dribble" out. If it is on shore, that draws critters, or if the water is shallow enough, those smart Blue Herons can learn the cycle times and wait in the shallow water for the little guys coming up next to shore!
I am hoping to get a Texas Hunter this winter.