I use a pinking blade on my rotary cutter. Pinking with a pair of pinking shears is a real pain unless you can sucker someone else into doing it. Clipping corners never seemed to work for me. The serging and staystitching work but are time consuming. I think the answer to this problem depends on what you are willing to do.

Toss them in a mesh laundry bag and run them through the washer. You'll get some fraying but it won't be as bad as doing it without. Plus it will save all that cutting