If you're both going in at the same time - why not get a team shower? That way you each get your own room.
Most showers have a deadbolt lock. If the door is still locked then the shower is still occupied, right?
Most have an inside lock. Wife and I used to leave separate quite a bit. One would get done and head back to truck or get supplies/food/etc. I don't miss showering at truck stops. I no longer shower at truck stops so my information could be out dated.
Hot water lovin'. Get the stank on, then get it right back off. And then go to sleep like a.... something that needs sleep more than anything else.... like a sloth! Yeah!
Then you have to wait for two showers to be available. Also then we only needed one toiletry bag. Wife and I had a system. Idea is to get showered and get down the road.
They weren't married, so I don't think they would have a case. This was about 5 or 6 years ago before all this stuff started.
Saw two men and their little dog heading to shower together today at the loves while getting my free coffee. It was interesting to say the least.