Easier for you and the other to from an entity, and have him sign a resolution stating that though the property is in his name, it is the entities. 

Did you rent through a STR company and if so, it may be best to go to them for resolution. 

Obviously I could have fixed that specific thing first (it's cheaper to re-route the downspout and cap the drain than it is to confirm that the underground pipe is actually broken, and based on the verbiage in his letter, he appears to feel the re-route is an acceptable resolution to his concerns).I met with an attorney friend, and he feels that the neighbor's behavior is harassment, and that now is the time to send a letter from an attorney telling him to knock it off.

I want to buy my own machines, collect money and manage service requrests.Hi Mike, did you ever get resolution on this issue? 

If you end up taking this to court I would be interested in hearing the resolution. 

Unfortunately, we were foolishly hoping for a quick resolution to this mess by going to small claims court.

Up until now, we have been using the Airbnb request payment service, however, the payouts come tagged as a "resolution".

What was your resolution?

Hopefully, once he realizes you can force a sale and WILL force a sale he will be more willing to negotiate a fair resolution to the situation. 

I don’t see a resolution anytime soon.