Those properties are currently cash flowing $3,815 per month but if they were paid off they would generate $6785.58 per month. 

I've spent the last 3 years nagging the city to sell me a lot next to my property so I can install a driveway and they've finally agreed.

The mortgage payment is $1,000 on each house, so you earn $500 per house or $2,000 monthly.

Typically with houses of this age - you'll need structural folks to dig and install piers into the soil.

But you should be able to target that upper demographic segment and still move a house in a few months if you are in the correct markets.

My net cash flow went from only $1600/month to 19k/month over the next 6 years.

Roughly $600 per month in positive cash flow.What made you interested in investing in this type of deal?

Quote from @Andrew Lawlor: I've been actively investing in short-term rental properties for the past three years, managing one live property and another that will go live in two months.

We would also like to know some strategies on lease renewals during non peak months.

If you need 6,000 a month that is 72,000 a year.