I think you build is nice. The sides and back are nice and strong. No overbuild in my opinion.
You can enjoy having a support for your body when you work in the tank in the future.
The only thing that concerns me a little bit is a possible bowing of your glass window.
Maybe it's just not clear in the pictures, but I don't see any support on the long side of the glass??
My tank is all glass, but it's holded together in a metal frame on the top with welded small bars to keep the glass from bowing. It put in a picture to make it more clear.
Maybe you can weld one or two bars from the glass to the back side to cover this?
Currently the glass is sitting in a hole up against the 2x6 wall. The wall is a supporting wall that holds the main floor of the house and the roof structure. So the wall shouldn't move. I also was told i only needed 5/8" annealed glass for this front wall but chose to go with 3/4" tempered glass (4x stronger than annealed).
All the being said, I appriciate the suggestion!!! It is a concern of mine and i have considered something like this. I saw a tank the same size as mine yesterday at a fish store in chicago. They also had bars like yours in the middle. Im going to look into the bars as i had only before looked into making it out of wood. The tank in chicago only had 1 1/2" thick side walls where mine will be 5" on the sides and 7" on the back. Do you think the bars that you have above yours could hold your body weight. I might consider this more if I could use them to support my weight as i try to clean the front glass.