Idea: one pair (and circuit) for ditch (wider dispersion for trail riding), and another for fog, which could be amber or a diffused white lamp. Bear in mind, most people prefer their fog lamps mounted on the bumper so the haze doesn't reflect back on them so much.
Idea #2: One ditch could be beam & aimed forward, the other (outboard) could be dispersed for side illumination.
Edit: Sure, people install two pairs of ditch lines at the A-pillar, but it strikes me as kind of gaudy. Mallcrawler "dress to impress," but to each his own. I have white dispersed fog lights at the bumper, and amber fogs on the A-pillar.