Sump/fuge for a large cube

[Ruth]

Overflow is 12" X 18" and has 5 holes (I think - it's still all wrapped up). 2" drain and 4 X 3/4" returns.
I don't think I could do the stacking thing with 2 separate tanks as the sump/fuge will be underneath the display and I also want this display to actually be lower than normal because my "plan" is to make it top down viewable for clams.
So far I have most of the equipment I will need - calcium reactor, tunzes, protein skimmer, return pump.
I am still a little undecided on how I want my lights to work. Initially I was going to go with 2 X 250W MH supplimented by VHO actinics for one "side" of the tank and 2 X 400W MH with Luminarc reflectors. I actually have this purchased but am now thinking that I may just want to go with 4 Luminarc 400W penants. I guess my question is how the heck would I suppliment this with some kind of VHO actinic? Could you just go with a fixture with only VHO and sort of run it down the middle?
Help and suggestions most appreciated.