Your success is my success.

Are you familiar with Lawton or have you seen a lot of successful investments there?

Quote from @Joe Paasch: I have joined this site to gain important incites, discussions and plans to build a successful portfolio.  

Congrats on your success so far.Some random thoughts for you:- It might be difficult to tap the equity in the rental at this time given the current state of interest rates. 

Here's an article with things to consider when selecting a cost segregation company.

The only other question I would suggest is that you do engage a property management company to review your quad and review your monthly financials.

To make the strategy successful, you need to find a property that can be acquired below market value.

Could you recommend a trustworthy and cost-effective company for this? 

But, the seller will never close a sale until the buyer releases that claim and withdraws the affidavit because a new buyer's title company will not issue a title policy and the new buyer's mortgage lender will not make a mortgage loan.Its not worth doing in this case but when real money is involved it is pretty effective.

I own 11 properties currently and I have only sold 1 in the past because it was a condo with a fraud HOA company.