This service also subs the legal work out. 

Is there a legal way to ensure they dont trash the place?

If you stay on the mortgage, you need to write out a legal agreement as to what happens when she sells (or if she finds another boyfriend/gets married). 

I carry a very small, very light 8 shot 22 caliber revolver everywhere that's legal.

This process is extensive, requiring community engagement and approval from the City Planning Commission and City Council.Given the predominance of multifamily residential properties in your area, there may be a precedent for such developments.

That is basically an extra tax return, legal fees for setup, bookkeeping costs (if you aren't doing it yourself), possibly an umbrella policy.

If the rents were collected after closing and they were not addressed in the sale, then you shouldn't have a legal obligation to give them anything.

BP has some and also you can use Legal Templates to create one.

With Tenant Turner, we can set specific requirements that prospective tenants need to meet before they’re approved to request a showing—such as rent-to-income ratio, pet policies, and other key criteria.

If you use a DSCR rental loan it could be as low as 3-6 months of time seasoning required so it depends on what product you're using to accomplish the mission/goal.The time frame isnt a legal requirement, its a financing product specific requirement as a guideline to obtaining the money in which you seek.If you had other scenario related questions feel free to mention them below or via DM.