Camber angles tell the story not visual appearance. For a 2007 the maximum allowable negative rear camber is -1.8 degrees. My preference would be to keep it at -1.2 to -1.5 degrees. Just as important is the rear toe setting where you want just a little toe-in. The rear toe spec range is +10 to +30 degrees (+ is toe in, - is toe out). Keep it close to +10 degrees or even less if the car is lowered. Excess camber + excess toe (even if both are within the spec range) = inside edge tire wear.
I would get the shims that bolt behind the hub, I just did an alignment on my car after I lowered it, the camber was -2.6L, -2.4R, I installed the bolts, got it to -2.0 and -1.9, i then put in the shims and now they are at -1.2, -1.1. You don't need alot of negative camber unless you corner really hard. it just chews up tires
Toe causes premature wear. Camber will cause uneven tread depth across the contact patch. 2 degrees negative camber can be run if you have good toe specs. I have no bolts and a coilover kit with an alignment for autocross and it does not eat tires. The specs are way better than a Ford or any garage specs. They just want everything in the green. 1.9 LR 2.1 RR