MHP is a mature space with many proven operators.

If you are going to pay for mentorship, find an experienced operator in your market or better yet, offer to invest in the experienced operators projects and get an inside look at their process and systems.

I'm a real estate agent and my wife is the operator of our senior living business.

Nothing wrong with LTR's - but what I like most about STR's is you are (usually) operating in better appreciating submarkets. 

It should be noted that the cases were prosecuted against companies that owned and sold thousands of properties nationwide, not against small time operators, but anyone who attempts to follow the model is better off hiring a well versed in the subject matter attorney and be aware of state specific restrictions (like in NY, Wisconsin and others) on Deed for Contract agreements.  

Here's the City link for you to reference. https://www.chicago.gov/city/en/depts/doh/provdrs/homeowners...1) ADU regulations specifically exclude Short-Term Rentals so don't do it if the intention is to short-term rental. 2) The ceiling height oh 6'10" is almost guaranteed to trigger digging a basement if you want to formalize as an ADU unit, especially if that height is further reduced by pipes or HVAC. 3)Ingress/egress is an issue for renting, as is that any bedroom also will need two (ie operable window/doorway).

Have you taken the time to search AirBNB and VRBO in those specific areas to see how many STRs are operating?

By year three, I aim to cover all operating costs and, by year four, to generate positive cash flow.Experienced investors say it’s crucial to persevere through the initial challenges while gradually building credibility through positive reviews, and I believe them.

The other is a smaller operation which does a lot of business in the specific neighborhood the house is in.  

You also need the operating cash to do rehab.I say this because you mention FHA and low money.