I don't see why not, but that might become a tad pricy if not used properly.
I mean, on the one hand, if you have a UniPak II per fixture as you suggested. But this can get expensive. For a bit less money, you can gain more control over more fixtures by using regular dimmer packs. If this is in a "Clustered" configuration, dimmer packs make more sense. Say, for example I am using a DP-DMX20L dimmer pack, and I have a Sunray III, Mystic, an Electra and a Rover in somewhat close proximity, I can simply hang that DP-DMX20L and use that to turn on/off each channel/fixture via a single 4-channel device, which is cheaper than 4 UniPakII's.
Now, say a Millenium on one Uni Pak II and your Fearsome Fours on Uni Pak II, I don't see that being a big issue. Each Uni Pak II can handle 10 amps, and the Fearson Four does come CLOSE to that , but not quite, so you're fine as far as current draw.
What I am saying is you have options. Your idea will work just fine with no real problems. You'd definately need to add some sort of DMX controller for sure into the mix, or you can use the 1-channel DMX controller for the UniPak II that it appears to inclde, but then you have to deal with that distance of that cable, which makes a DMX controller make more sense.
A note you need to take into consideration:
The Uni Pak II, like the latest DP-DMX20L's, offering the option of setting your channels/ports to switched(on/off) or dimming(variable voltage output). Dimming is only good for traditional incandescent can-lights, such as par 38's, Par56's and Par64s(to name a few. Par 48's and Par36's come to mind as well). You need to set your pack's channel(s) to SWITCHING mode when using with a High-Tech fixture because the fixture is designed to be full on or full OFF. Reduced voltage can cause unpredictable results, which will ultimately lead to electrical damage. Switching is either ON or OFF, based on a threshhold setting, typically anything DMD value below 127 is OFF and above 128 is FULL ON.
Dimming: Cans. Switching: Hi-tech
Intels: DO NOT HOOK TO DIMMERS/Switchers. But you know that one already.
If you choose to go with the Uni Pak II for the Fearson Fours, you'll need some extension cables and splits just to get it all working properly, just as you do now without it, so nothing new there. Just swing your power input to the Uni Pak II and you're golden. If you choose to go with a DP-DMX20L, that dimmer/switcher can be set to 1, 2 and 4 channel DMX mode. So, you could turn it into a single power distro for your Fearsome Fours if you wanted to, but I wouldn't recommend that only because that dimmer could be better utilized in my opinion.
Dimmer packs and switcher packs definately bring control and otpions to older lights while letting them mix and match with cooler newer stuff.
Since you mention DMX controllers, the DMX Operator is a great controller for your application. Cheaper than the Pro, tons of options. But, if you insist on the DMX Operator Pro, you'd probably want to put those on the "fixtures" side of things. The "Conventionals" is intended to be used with Par Cans and regular dimmers. Even though you are using dimmers, this application is more "fixture" than conventional.
Any questions, feel free to ask.
If it was me:
DMX Operator(I have one, I'm preferential) for control.
1 DP-DMX20L set in 2 channel and all ports set for switching. Attach power cables as necessary.
Accucable as necessary
DMX Terminator in the DMX OUT port on the DP-DMX20L.
Address the Dimmer pack starting at 1.
Plug Millenium into the plugs marked 1.
Plug the Fearsom Fours into the power ports on 3 and 4.
Attach extensions as necessary.
Need to control?
Hit Fixture 1. Fader 1 is Millenium, Fader 2 is Fearsom Fours.
There ya go.
That's how I'd do it. Granted, I have the DMX Operator and the DP-DMX20L but my dimmer packs are older and do not support switching, but that's OK because I don't use them on high-tech lights.
The latest DP-DMX20L replaces both the older DP-DMX20L and the PP-DMX20L power pack(switching/relay). The latest DP-DMX20L puts the power of both into one package, keeping the DP-DMX20L as is at it's core, but adding the switching option per channel to take advantage of the relay/switching functionality of the PP-DMX20L.
Enjoy, have fun, rock on!