I have a single family house that I’ve been house-hacking by renting out 3 of the bedrooms.

I'd rather they stay because my housing is exceptional. 

This is my 3rd tour in Germany and I am also seeking to purchase rental property here as well.Finally, I am planning to do my first house hack upon my return to Baltimore next year.

And only after you spend time, money and effort, finding "people" will you ask them "hey sell me your house".Now, how many people do you need to ask this question before you not only get a "yes"...

I used all that cash to buy 3 more houses.

Then you can repeat and pull the pallet you want to use on each house.   

As a result, I'll be selling my house and using the gains to put a down payment on a secondary house next to my current rental property.

I have several rentals, but just listed one that I am managing myself and I am overwhelmed by the number of people who are calling about Section 8 housing.

My family of 6 live and own in a ranch style 3br/2.5ba house with completed bonus room upstairs in a HOA neighboorhood.

Some areas have specific departments or webpages dedicated to housing or zoning regulations that can provide detailed information.Another effective approach is to connect with local real estate agents or property managers who specialize in short-term rentals.