I would consider the following (which you may have already done):House rules say no gatherings (penalty of $X per person if violated)House rules say quiet hours are 10:00 PM - 8:00 AMIf profile has no reviews / not verified, require they confirm the # of people who will be at the property & agesUse a noise monitoring system like Minut or Noiseaware (disclose in listing)Use exterior cameras to monitor driveway (disclose in listing)But at the end of the day, there are still bad guests who will get through and sometimes you just have to file a claim, kick them out, apologize to neighbors, and get the place ready for the next group.

Bigger Pockets has some great state forums and usually there are good locals that monitor those.

I don’t use a noise monitoring sensor in any of mine at the moment.

Do enough people slip through that it would be worth paying for a service on a monthly basis to be able to pick up the phone and have someone come shut down the party/monitor the property to stop a party before is starts, i.e. more people arrive than listed on the reservation? 

Bigger Pockets has some great state forums and usually there are good locals that monitor those.

Does anyone have a vendor they can recommend that monitors & pays property taxes for NPNs and REOs?

Definitely install some sort of smart lock that automatically generates access codes for your guests, try bookkeeping software like Stessa, and use a Ring doorbell camera to monitor who is coming and going.Good luck and keep us posted with your progress!

Bigger Pockets has some great state forums and usually there are good locals that monitor those.

Bigger Pockets has some great state forums and usually there are good locals that monitor those.

There are usually some good, local investors that monitor those forums.