Adam has posted about this previously and has a slightly different / higher aim than i run but...
generally, I find a spot where i have a flat surface to aim at and on level ground. Using headlights as a reference, mark your headlight “hot spots”. the distance is somewhat significant and the truck needs to be unloaded for this- no cargo. Your headlights are aimed to hit the pavement not terribly far out, so they’re not aimed level with the ground.
Your fogs are lower than the headlights. Measure your distances
ground to center of fog light center of lens
ground to low beam center of lens.
I aimed mine at about 10 yards, the wide corner lenses may make this more challenging. Move in if you have to.
Using painters tape, i marked the wall with my center of hot spot reference points for the headlights on low beam.
fire up fogs one circuit at a time and cover 1 lens. Aim the other. I want the hot spot of the beam just slightly lower on the wall than height to center of the lens. aiming 1x1, measure the hotspot center height and relation to the low beam hot spot so they are pointing straight ahead. when you’re done, pull the painters tape and go try them out in real life situations.
You may want them aimed somewhat differently, depending on your intended use, but this method will get them in the ball park.