I'm going to install a display 5 gallon refugium under my stand. I'll be cutting the bottom 2/3 off my cabinet door.
The tank is currently being built (12x10x11"). The tank will come about 2/3 of the way up the cabinet door opening. It should allow reasonable, albeit tight access to the 'fuge and powerbars (mounted on the inside top of the stand). I've designed, built, and tested my PVC continuous siphon overflow. I've tested it with 200 gph, but I'll only need it for about 100gph (or whatever a MJ1200 puts out at 3.5' head). It will be primed with a maxi-jet venturi.
The next step will be building the baffles for the back compartments of the refugium. That will have to wait until I get the tank. I'm allowing space for an AC70 sponge and other media, since I don't run a mechanical filter on my tank, and I want something to remove the detritus before it gets to the rather low-flow 'fuge. I'm planning on some macro, a bit of rock, and a seahorse or two.