Well, a small screw up on my end. I should have remembered Derek's (Losai) experience with his corner overflow Tenecor.
Basically, I do not have enough clearance for the bulkheads in the floor of the tank in the two back corners. Luckily I figured this out while the stand is still in the shop. The welder told me he is not too busy now, so he can fix it. It is going to be unsupported for 9X9 inches in the two back corners; I will just have one inch plywood there, no metal underneath. That way I can drill holes in the wood and fit my bulkeads.
This is a classic example where I could have (should have?) learned from some one else's experience....
I am guessing it will be an extra $300 lesson for me?