If you really hustle and are smarter than the average bear, you may make enough money that you can buy an investment property.

A high property tax rate will increase the taxes more quickly as a percentage of total expenses when the property value increases.

As a former business owner, there are times of the month where it seems that all the cash goes out at once.

I  Income:  The amount of property you can buy will be dependent on your Debt to Income ratio.  

I would also add that you join your local REIA chapter (Real Estate Investor Association) as it will allow you to network with other STR owners and get more location-specific information. 

Working on an owner finance deal and I'm curious what technology you use to keep track of payments and amortization schedules.  

STR Property management is common and I know a lot of folks doing this.  

In the event that a seller was to owner finance a property to a buyer without a SSN, is there a market for the Note to be sold to a note buyer?  

Since part of your property is a rental, I believe a portion of your mortgage interest should be a tax deduction unlike your other debt.

So the property owner can never sell?