Doubt a Pom will be able to move a 4 piece play pen but just in case, you can just block it with a pail of dirty clothes or water.

When you are home, let your dog out and play with it. Burn all it's energy and when it's time to go to bed, let it go to bed. If you feel that you need to use a muzzle, then by all means - better than people complain and get into trouble.

Muzzle may seem cruel but if you sleep, your mouth also close. Open also not that big, provided you dont tie too tight. Give some space and untie and let it drink water in the morning.

Yea, I think that's a possibility too... Maybe you should let them sleep separately? In a different room, arrival of new smell to conquer her spot. Hehe..