Does it slip down over the entire pad and cover the back as well? If not, you're still open to moisture problems. Mine doesn't have that cover so after sealing the inside by separating the two halves and adding some around the area, I then ran a small bead of RTV around the perimeter in back as well as around the cable entry point. I've been in some horrendous storms with no troubles in the six years it has been on there. I also removed the connector that's a couple feet from the control bad and hardwired it together. That's another point of entry for the elements.
It wraps around and covers most of the back, but you would still want to seal around the wiring as it is exposed.