Electronic Leveling Control. OEM air shocks. They keep the car riding the same height regardless of spring wear so camber isn't a problem. GM doesn't make camber bolts. They are much smaller diameter than OEM and aftermarket. That'* the concern. Although many are used and people seem to have good luck with them.
Camber plates are another thing. They adjust camber from the top, expensive, and alot of labor thus $$$ to use them. You find these more on raised trucks, show cars of higher/lower heights, and race cars with custom suspension setups.
IMO< looking to the rear for shaking you describe is not likely. Usually that would take an extreme toe misalignment. I ran my car at different heights routinely with bagged suspension where the camber was at the will of given height, and never had any shaking with my Bonneville.
I would be looking at front toe misalignment (Bad Tech), bent front end control arm, control arm or sway bar bushings shot or tire unbalanced (lost weight) Except in more extreme cases camber misalignment more likely to cause premature tire wear, and/or cupping. Not shaking.