3x3 coco flood table setup?

Trying to set up a table for some coco pots in a 3x3 tent. I can't find a decent tray thats the right size...am I missing something? If i put a 36" tray in a 36" tent, that will totally block my intake vents... how do you guys use these trays such as botanicare's od series? Do you really need to get a tray a whole 30% smaller than the tent? Wth.

Get a 24 x 24 inch tray for a 3x3 tent. The size is the interior reservoir dimensions. The outside size is more like 30 x 30 inches.

Or you can build a diy table from 2x4s plywood and a pond liner pretty easily.