set up looks good.... I would probally run each one to a common sump... and link them that way....this way each one runs to the bio...instead of one to one and then to the sump...
Here is a shot of my rubbermaid. This is where I keep all my males at when the females are gravid. The top is made out of pvc and a piece of hot tub cover material. I made it so it fits over the sides of the rubbermaid, not just flat on top.
Now for the overflow. It is a 6"x6"x about 16" (I forget the exact measurement but it fits just shy of those bump outs on the rubbermaid) acrylic box with a lip about 1/2 from the top to hold the eggcrate in place. The bulkheads have 2 gaskets on them. One on the inside of the overflowbox as you would normally install a bulkhead. The other one is between the overflow box and the inside of the rubbermaid. You have to be precise when you line up the holes in the rubbermaid and the overflow box so they line up and you get a good seal. I've considered manufacturing some of these and selling them because they work really well for me.
Dave... I would love to get 2 of those from ya .. I was trying to think of how I would create overflows for those rubbermaids, but you answered my questions.. If not, I can attempt to make my own, but it won't look that nice! (or probably work as well!)