Overnighting in rest areas has come up various times in different threads as I recall.
We've used rest areas to sleep from 4 to 8 hours many times when traveling between home and family. Don't recall it ever being part of a vacation because we take it easier and drive shorter days. Rest areas meet our needs much better than campgrounds when driving late regardless of cost.
Most of our stops have been on I-10 in Florida, Alabama, or Mississippi; or I-75 in Florida. We've also stopped one or two nights each in Arkansas, North Carolina, and Georgia while driving to visit family.
As I've mentioned before, our van is only 20-feet long so we park next to cars where there are a lot more people sleeping, and it's not as loud because trucks are farther away. We have never been bothered, and haven't seen anyone that's been asked to leave.
As long as there are many open spaces, I doubt there is going to be an issue. However, there have been a few recent reports of upcoming campground shortages that may change our ability to overnight in rest areas. I hope it doesn't come to that.