I agree with previous poster, take a look at the NRMP to give you a idea of what baseline is for people getting accepted into plastic surgery programs.
I don't know how good you are at standardized tests, but do everything in your power to hit a homerun on Step 2, you probably need >250 to try and overcome the Step 1 score. But realize even with that, programs will still have minimum cut-off scores in order to view your file and several of the California schools won't look at your file unless you are >240. You need to be strategic with your aways and you need to absolutely destroy them, you only need one program to fall in love with you, and I have known people who only got 1 plastic surgery interview and still matched.
Realize that this will be an uphill battle, and you will need to be extremely pro-active at getting LOR's from your home institution. I would also advise to try and spend as much time with your program as you can to get a more personalized letter. The personalized letters will help you a lot more than any form letter from an away rotation that doesn't know you very well.