I think the best way to handle this is going to be raising the entire tanks onto 4x4s, then using baseboard to close off the gap it will create at the bottom. I'm trying to find specs for compression load of lumber but it's all about weight over span and not fully supported. I assume it will be just fine, but I'd rather find out now than when I start filling it with water.
The issue in my mind, is I'd like to be about an inch or two below that bubble trap wall for the return chamber. , maybe having the centerline of that hole being at the 9" mark. That would put it well below the drain, but a 4x4 would space it up appropriately
I also failed to account for a p trap in this setup, so that would let me point the drain exists down and use the droop of the hose to hold enough water for a makeshift p trap...at least that's how it works in my head. I'm well out of my element.
