It appears to me that your alignment guy didn't touch the rear alignment at all. Your new rear tires are going to wear just like the old ones did, and in the same time frame. If you have an IRS rear, that much negative camber is unnecessary and tire-wearing.
As I've said before, adjust rear camber, then toe FIRST and set the proper thrust angle. Then and only then move on to the front.
You definitely want MORE caster in front than you have. Doesn't matter if you cruise or thrash the car. The shim hints are great.
I realize I'm the only one who says this(and nobody listens), but the aftermarket camber adjusters will give you MORE caster if you don't use them to give you extra camber. Think about it, it works, and will tilt the spindles back a degree or two and give you extra caster.
Or do the shims, and I totally agree with Al and Rick. Put two on one side and one on the other and it will even out the caster side-to-side.