ANSWERS IN ALL CAPS:

Not sure if round is as good as rectangular. If you've done some research, which it appears you have, you will note there aren't any round hauling tanks for commerical hauling on the market. It may just be there there is less space wasted with a rectangular tank. A couple of compartments may be a plus on the large tank too (if it was rectangular).

ROUND IS A MUST WHEN HAULING SHAD. IF NOT THEY JUST BUNCH UP IN THE CORNERS AND DIE (MY EXPERIENCE). IM GUESSING THE TANKS ARE MAINLY RECTANGULAR DUE TO MANUFACTURABILITY. BASICALLY IT IS EASIER TO CREATE A SQUARE AS OPPOSED TO A CYLINDER. HOWEVER, YOU HAVE A GREAT POINT ON MULTIPLE COMPARTMENTS.

Here's a rectangular plastic insulated tank I own from Rotomold in Minnesota.




I'm not a big fan of the bulkhead where a large PVC pipe is connected for quick release of fish. The fish don't always cooperate. I've had yellow perch that just flounder in the bottom of the tank once the water is released.

WHAT TYPE OF RELEASE DO YOU LIKE? NETTING AND RELEASING?