And is mileage looking for additional rentals and flips in markets you currently own properties in, deductible, if you operate out of your home office? 

I would also show up at local REI meetups to see who others are talking to in order to fill their MTR units.

Quote from @Dave Hart: In the weeds on this one.

Excuses don't count and the judge will find in your favor.

We also keep an inexpensive steam cleaner in a closet in case there are any accidents.

Interested in hearing how others deal with it.

It sounds like you're in a great position with your investment property.

I started back in the days where foreclosures were abundant.

I can understand the temptation of wanting more rent from your multifamily home however I would add this to your train of thought:What would happen if your tenant in your illegal basement unit burned down the house which caused another tenant to get hurt or even die?

Every system you try will have flaws, or you may salivate over a feature that appears in other software.Some familiar names are mentioned frequently: Stessa, Apartments.com, RentRedi, TenantCloud, Innago, RentManager, Avail, Rentec Direct, Doorloop, etc.I recommend conducting thorough research on each app online to understand their offerings, pricing, etc.