You could. It's essentially the same process whether you're doing low-beam reflector, low-beam projector, or fogs. Just different bulbs and different ballast mounting locations. I can post pictures of my cutoff from my HIDs in Hella projectors if you would like some more variety and see how it looks? Also, did you end up keeping your HIDs in the low-beam reflectors, or did you go back to halogen?
And in terms of your edit on the fogs and not getting pulled over, most people conclude that since they are so low to the ground, the glare is so minimal that no one bothers you about it. I have yet to do it to my fogs, but plan on doing it soon. I currently have Nokya Hyper Yellow 2500k halogen bulbs in my fogs and they look fantastic. But, my dad recently bought a new car which coincidentally uses the same bulbs as the Focus and he likes the looks of my yellow fogs, so I might as well upgrade mine and give him my Nokya bulbs.
2001 Ford Focus SE, Black - R.I.P.
2001 Ford Focus ZTS, Silver - Hella Dual-Projector Headlamps Painted, Morimoto 5000k 35w H9 kit, eBay CAI