Good catch on the two circled pieces. I will make that change. Thank you.
The extension is simply an open ledge for equipment and also so I could stand on the work on the inside of the tank.
The tank itself will not come out that far.
I would install cross members with plywood and make them even with the stand this way when you level stand both tank and sump will be level
It doesn't show but it will lay plywood on the bottom and sit the sump on top of that.
A feature I wish I had done....Melev of melevsreef had a cool feature I wish I had done. He built "pockets" in his stand that allowed him to add a plank or extension to walk around. For ease of reaching/working into tank.