Need? definitely not. Helpful though. I use the timer, and the alarms on the controllers. It is nice to know when the kettle is 'about' to boil, or when the strike water is ready, etc... And I use the boil PID to measure temperatures elsewhere during the mash, particularly when I was tuning in the system and tracking down temp control problems
I bought the box off ebrewsupply, so it might not be the same panel. I'll measure tonight, anyways, and give the dimensions. Based on your drawing, though, I'm sure you are fine.