Well, after a trip to my local Firestone (they got a great guy working the alignment machine, let me under the car while he did his work and whatnot), it is as I feared - my factory camber adjustment is maxed out:
Due to my tire sizing (255/40/19 F and 295/30/19 R), the front of my car has a taller overall diameter tire/wheel combo, and after lowering the car to a point where the car only rubs on the plastic fender liner on hard bumps, the rear of the car still has a tad of fender gap. I may decide to switch back to my stock front RE050A to get a smaller diameter, and then looking for a lower profile front tire, like a 255/35/19. Either way, I do need camber arms, front and rear, if I decide to lower more. The opposite end of that is to find a taller rear tire, probably stepping up to a 305/30/19.