Thank you all for your answers!

For Wyoming Rest Areas, sleeping in parked RV is permitted.

Yes

Signs there say no camping. I was just there a week ago. "Camping" is a little vague though. Setting up shop to stay for a couple day? Certainly not. Parking without disconnecting or deploying stabilizers/levelers? Maybe. It's not cut and dried. There may be truckers that stop to sleep for a few hours. So how is that any different than an RV that stops to sleep at night? It would be more clear if a sign said, "4 Hour Parking Only." There is dispersed camping within 30 miles, so that's always an option. Or the three truck stops just north of the rest area.

Yes