alignment help!

today i go to the tire shop
i thought my front end was out because there was some tire wear on the outside of the tires
turns out my front end is fine, but my back end is pretty ****ed up
the right rear has some negative camber i dont remember how much
but the left rear has ****ing 1.5 degrees negative camber. my shit isn't even lowered!
but i was thinking, instead of paying 500 bucks for labor and new rear adjustable control arms, can i use the washer technique for the rear like other people do for their rear when they lower their suspension? its the same situation right? my rear has negative camber just as if it were lowered, just it isn't. or if there is anything else you guys can help me out with in this situation, it would be MUCH appreciated. :(