I want this to be acceptable long term if I keep this method of financing. 

There are also people who swear by one method or another.   

What methods are you considering doing?

I’m focused on buy-and-hold properties, fix-and-flips, and exploring the BRRRR method.

For example, we've recently taken over marketing internally because the property management company was not experienced enough in using the newer advertising methods we need to pursue.

I take a methodical and pragmatic work approach. 

If you are open to non-traditional methods of financing, you could use a debt service loan to bypass that requirement.

Many opt for other investing methods in their SDIRA like private lending, crypto, private equity...anything except collectibles and life insurance.Note that a Solo 401k is exempt from UBIT on leveraged real estate so if you have self employment activity and no full time employees save for you and your spouse you should consider the Solo K as an option. 

Used houses in the area sell anywhere from $75-125 a square foot.These are long term rentals that I do not plan to sell.I am reading the Rental Property Investing book and implementing the method that focuses on cash flow and that strategy states you need to have $300 cash flow per month, per property.

Probably going to be a check.Smart contractors are starting to understand that convenience matters to customers and being able to take different methods of payment can help them collect their money.