This would include architectural fees, new equipment, cost of protecting or defending your title to the property, or building improvements.

Now, we want to run the rental portion as a business, but we understand that with the house in our names, there’s not a great way to protect our assets without quitclaiming the deed to an LLC, which we cannot do because of the due on sale clause in our mortgage. 

I recommend reading this article by Marty Boardman: https://www.biggerpockets.com/...Secondly, an LLC isn't really necessary for wholesaling unless if you have assets that require protection.

What checks I need to do to protect the investment?

We are talking about switching up the game plan a little and using the BRRR method. 

Looking to expand my portfolio to other states and am looking for ideas on good corporate structures that can provide protection and allow me to add additional real estate into it. 

How do you protect your clients from making the same mistakes? 

We have a 14-page management contract that we've added our real experiences to over the years, with the intent of protecting both us AND the landlord.

I switched to Texas and was beat out on the first two, but got the third which was the best of the three.

And until you are comfortable with all the paperwork, I highly recommend you have a trusted mentor, or you hire a quality real estate attorney, to advise you in order to protect your interests.