It looks like it but really isn't. I built a rectangular frame, faced it with maple plywood. Basically the same as you did. The trim is just 1X4's screwed in from the inside of the cabinet and the top piece covers the tank frame. Those corner trim pcs on the tank itself are simply siliconed on. Hey, it may be up for sale in the near future...and Olean isn't too far...
I think Ill have to get some more space befor I go to the 90 gallon size. Which means a better job and apartment Being 20 and haveing a girlfriend = not very much money!