I'm not a trucker and haven't engaged in any of this kind of activity. However, I recently was on a road trip and was driving through Connecticut around 10 PM until midnight. I stopped at a rest area to take a leak and on the way in traffic came to a complete stop, as little traffic as there was because cops were going through checking the cabs of all the trucks that were parked there. CT seems like they allow some weird behavior with truckers as I noticed that they seemed to be parked everywhere along the highway which I haven't noticed in any other state, and this rest area was completely full.
The cops that had traffic stopped were dealing with a specific truck. I didn't see enough to know what was going on but there was someone in the truck and the police were talking to them trying to get them to come out while other cops were looking in the woods on either side of the road looking for something, no idea what.
As I got through that bottleneck I pulled into the area for cars and immediately saw a guy, probably in his 60s next to the open door of someones car and wearing no pants. He was right in my headlights and didn't seem to care, the cops lights were still visible in my rear view mirror.
I found out that the rest areas in CT actually close at 10 PM, I'm not sure why, but it meant that the only place to piss was a port-o-potty, so I used that, bought a drink from a vending machine and left, but not before noticing a lot of guys kind of walking around the area. There was enough activity that it because very obvious what was going on.
I decided to check out the other rest areas in CT on that trip to see if it was similar, and it was. Every rest area I stopped at had some kind of activity going on. I didn't join in, but if I wanted to then that was certainly an easy place to get it done. I crossed into Massachusetts and that activity stopped completely. For some reason CT has a lot of anonymous hook ups between guys at rest stops.
I also was in NY once and had to pull into a text stop area to change my shirt, weird story that isn't worth telling. But I noticed while I was changing my shirt that there were several guys standing far from the road, dressed as though they had just left their office job. It wasn't as blatant as what I saw in CT, but still pretty obvious what they were doing there.