Examples to kick it off: adding solar panels, vending machines, advertising space, allowing credit card rent payments w/ fee. 

I can tell you about properties I have bought (and am still buying) between $1,300 and $30,000 that are worth 6x and over 1000x more today and have been generating rent every year on top of that appreciation.  

The median single family home in Montgomery costs $458,000, which is a 7.13% increase from last month but a 6.77%increase year over year.

I've been building a 1 bedroom carriage house on the property in my spare time for the last few years which my wife and I plan to move into in the next few months so we can rent out the house.

My end goal is purchase a duplex or multi-family home and rent out the property for passive income.

What are other rooms renting out for in the area? 

Too many sellers are asking for prices based on the park being at market rent for 100% occupancy.

There are known "aggressive breeds" that constitute a combination of size, temperament, etc. to form this list of aggressive breeds which would theoretically be more of a liability.I also settled on a pet deposit, not a pet fee or pet rent. 

One unit is a 1/1 rented for $900 and the other is a 2/1 that could rent for $1,200-1,300.

I said there was no reason to sell the property (as rent would easily pay the mortgages, taxes, and insurance).