The crossmembers will sag over time resulting in negative camber. Yes, it can be corrected with shims to a point. If you run out of room on the studs for more shims, you will need to install offset upper inner control arm shafts. What you didn't mention is how much negative camber you have. If it is 5/8 degree or less, I would leave it as is.
To adjust camber without affecting caster, add equal amounts of shims to both bolts.