You'll want to be guided on the transaction in terms of documentation needed.

At this point I would pay $10 per month but I've seen much higher costs and the common requirement to process financial transactions, I just use the bank for that and check on taxes and insurance payments once per year using a calendar reminder to prompt me. 

Even if he tries to sue he'd most likely lose if you have all this documented.

As long as she has documented and confirmable income that covers the rent that's the major point to me.

We (buyer) signed closing documents a week ago and all parties (wholesaler, lender, escrow) are ready to close.

We document everything.

There is no other documents that would show where the difference went.

You could be escaping Florida’s escalating insurance, or Texas’ property tax.

Buy in areas that are less susceptible to large insurance increases (which is getting harder to do)

Also, one thing I’ve seen firsthand is that good bookkeeping and clean documentation make all the difference once you start juggling multiple businesses and properties.