CA is fine with sleeping overnight at rest stops, but no camping. I'm sure you can figure out the difference.
Also, enforcement of silly rules at CA rest stops is lax at best. If you park and climb in the back, you'll not be bothered, other than by noise.
I've spent many quick nights in our rest stops. When possible, I pull away from the parking close to the rest area. Sometimes even parking along the apron of the exit driveway. Overflow parking tends to go there anyway. Never has been an issue, and of course is quieter.
Buttonwillow is a large rest area (has sites on both sides of the interstate). Choose where you park wisely and I don't think noise will be much of an issue. Depending on how soundly you sleep of course.