STRETCH somewhat to get to the NEXT level, but a huge stretch is probably going to be a waste of time.   

Yes the next one will not cash flow unless a large down or you are out in the desert somewhere with low purchase price. 

Hangar space has a relatively low cost per square ft and it's not uncommon for tenants to shove cars, RVs, boats, etc into the empty space around an airplane but this will violate airport rules and regulations.PS I have on about a half dozen occasions seen private airports for sale on craigslist. 

Unfortunately this is a low income working class area. 

As the landlord we set the standard, I set my security deposit based on the risk level to me as the owner / manager. 

The second property will be purchased with a mortgage (you can determine how high or low the leverage will be by adjusting the proceeds you use or the price point of the 2nd replacement).You are adding some measured debt at a level that your dad can be comfortable with. 

Once you narrow in on what you're looking for there are some excellent lenders through BP that could help you find some good options for loans.For instance, if you needed to put as low down as possible you could look into an owner-occupied loan like a FHA loan.   

Basically I would not like the situation when I work with one arm of Chicago bureaucracy to pull permits while the other arm is sending bulldoggers to level my place.

Then they start trusting me lol.The ones asking you to reduce your commission and low ball, cut them and move on.

Since his mortgage is so low and we have really good relationship would be good if possible.