Gotta love small towns. Even if it isn't your in-laws, it would end up being someone. For some reason, people seem to think everyone should knock but them. I've had people come to my home and barge in when my husband and I were having some "fun" on the stairs; when I was doing barre exercises in the nude; when I'd just gotten out of the shower and was enjoying some private time with my good friend, BOB; and a few others times that I've preferred to forget. A locked door didn't work -- everyone knew where the spare key was even if I moved it and, if they couldn't find the key, they weren't above forcing open a window ... I might have fallen and couldn't get up, ya know.
Farmer's Markets are awesome, especially small town ones. I really miss the one back home. There was always a concert on Thursdays -- some much better than others.
When you get a chance, get a bike and start riding around the town. I've found that towns that aren't planned (Vegas was planned) were frequently set up around one main point -- all roads lead to it somehow. So, a bike makes it easier to meander around and find what you're looking for until you get to know the lay of the land.
Hopefully, you'll be able to work things out with your in-laws. I did have one friend who barged in more than the others. We finally came up with a signal -- if the teddy bear was in the window, do not, under any circumstances but bones sticking out or arterial blood, come to the door. If she did, I would not stop what I was doing -- whether it was dancing in the nude, entertaining myself or just reading a book -- she was at risk of what she would see. I don't know if you could quite work out the same kind of deal with your mother in law, but it might not hurt to try. Good luck!