0% Business credit cards + hard money loan = 0 money out of pocket.

Also be aware of Unrelated Business Income Tax (or UBIT) on leveraged real estate inside of an IRA.Or better yet, since you are self-employed - go with a truly self-directed Solo 401k plan, which would be a much better option and will help you avoid the UBIT on this investment.

I'm a retired engineer and have been successfully using income from these houses to support my retirement without dipping into retirement savings.I'm transitioning my business from rentals to a franchise and would consider selling one of my houses (5 br/4 ba - the other houses my son while he's still attending).

There are a handful of active agents here on BP in the Portland area (including my business partner and I) who would be good places to start.

She also mentioned that they’ve been in real estate since 2006 and have managed over 30 properties (though this is more of a side business for them), which suggests a mom-and-pop operation.

If I'm staying one night somewhere, a quick business trip or something into Denver to show clients homes, a hotel is my choice.

and they're difficult to do, because you're up against businesses that do nothing but flip and BRRRR, and here you come along wanting to do 1 home run right out of the gate. 

I like the business model with them really helping get it all set up.

You cannot maintain a business with negative cashflow. 

Do you want to own your own real estate like an apartment or retail center and create a side business?