Judging by the shape of the reflector, the fact the HID isn't shielded, and the fact you can't aim those lights, I'd be worried they would be too bright for normal road use and would cause lots of offensive glare for oncoming drivers. I'd also be concerned about possibly melting the housings as they weren't designed out of as heat resistant materials at headlights are.
Gm did make factory foglights that fit below the bumper, and also have a airdam for them. My 88 has a set that I modified to accept HIDs and are properly shielded to not be offensive to other drivers.
I like the ideas your coming up with though, HIDs are a very versatile lighting that we haven't fully tapped into yet. Did you see my non-projector HID conversion thread for my 88?! I modified all of my forward lighting and used e-code housings with proper shielding to create a very usable light output that has a defined cutoff line and isn't offensive to other drivers
http://www.thetruckstop.us/forum/showthread.php?20464-88GMCtruck-s-non-projector-HID-conversion