awcurl.. that beveled cut out is a HUGE HELP! I did that to mine too and it helps the light get in to the entire tank (the front). It is also a help for when you stick your hands in. If I upgrade my tank later, I am going to make that even bigger.
louis... let me know how it comes along!! I live close to you and I did a in wall tank. You are welcome to come check it out and get some ideas. Yuo can see pics in my gallery (pics are old now and since then added new equipment). If you're going to put it in your garage, I would do what I did.. and add 2 strong fans blowing cool air from the inside of your home to the top of your tank. I dotn own a chiller but will soon because I am afraid that my AC may go out one day.. or an electrical outage (generator will be used to power chiller). I have gone all summer without a chiller and have had my temps stay under 82.. august is where I hit 82.. in july.. it was under 80. And i also need to sheetrock/insulate the rest of my garage.
Good luck on your planning. Let me know if you need any assistance.