This practice simply is not scalable.Never cater to tenants by picking up rent. 

The same investment seeking 12% requires a lot more work, some more risk, and more time to put together a portfolio of notes.For someone who wants to enter the note BUSINESS as opposed to just investing their own funds in notes, the learning curve, time, effort and knowledge needed is much greater.

There are indoor units that have plumbing to route exhaust outside and outdoor units that are simply vented.

@Anthony CapaldiThe best advice I could give you would be simply this; Know that it's okay to walk away from a deal if the numbers don't work. 

The mileage simply won't add up because of the unrecorded personal trips.I DO want to play by the rules, don't get me wrong on that, but I want to keep it simple.

Each time you try to schedule work, and the tenant does not allow the worker to enter.

Congratulations on entering the path!!!

I have a one-page extension that says the lease is extended for XX months with a new termination date of (enter date).

Plus abiding by the lease helps take some emotion out of the decision as you are simply following the mutually agreed upon terms and procedures.

Less cost to enter the market, less demanding tenants (if you screen them correctly), and more opportunity for value add which is critical to generating solid cash flow.