Having the ability to live for free, while minimizing the taxes on my W2 income.

Here's the instructions:https://www.phila.gov/departments/board-of-revision-of-taxes...

There is no pass on the taxes.

Adding taxes and insurance would be an even higher payment. 

@Nathan M kieferI recommend that you get professional financial/tax advice.

With 3 properties already, you're definitely not "new" anymore ;-) Doing a refi is very possible (depending on how much equity you've accumulated) to do those types of things...the issue can be the tax ramification that you face if/when you do it.

.- Taxes are usually much lower the first year. 

Finding good deals is nearly impossible with the prices, tenant laws, and taxes working against us.Since you’re considering the Midwest, I’d definitely suggest keeping Detroit on your radar.

However, if you're running your numbers then you'll want to make sure that you're including all the interested paid for the money borrowed from your HELOC as well as the carrying costs including utilities, insurance and property taxes.

While this is less tax efficient, it would be less work / less stress.