Brodie, this probably isn't a good idea. YES, there isn't anything wrong with dual PSU's, but it is in the implimentation. A dual setup with a REDUNDANT PSU would be a cool mod. I agree with some of the previous posts about this not being a very good idea.
The major problem with this, is that EVERY source of cooling in the case will be linked to a PSU other than what the rest of the components are linked to. What will you do if something should happen, and power is cut to the "cooling" PSU (such as if that unit is unplugged, or if someone switches it off).? Then your main components will be left running with only a heatsink for cooling.
The second problem, is that the PCI power connection bracket you linked, is for linking power to the OUTSIDE of the case. So you would have to mod that panel to switch around the connections. You would be better off modding a PCI slot filler plate to do the same thing, and save the $6.
Lastly, let say hypothetically you DID do this? Why on Earth would you want the PSU to be OUTSIDE of the case. I personally would likely find it to be an unsightly mod. It would look better on the inside.