We also have interest from some new car companies that are looking at the facilities in Windsor for re-purposing to use for EV manufacturing.

Investing in real estate in actually starting, managing, and marketing a company. 

(you need to differentiate when a Mark Spain type company is running radio ads to attract business for themselves from it actually helping you out)4) Our TEAM or BROKERAGE has sold "X" homes!

Do you recommend making relationship with property management companies?

If you math it out it is probably unlikely that you will be cash flowing on a property that you are using 100% leverage on from a turnkey company.

For example, could I use my SDIRA to operate a management company that charges my holding LLCs a management fee?

They must be very low odds because insurance companies are in the business of making money, not paying out maximums.

A solution company that intrigues me is Acoustimac.

Some of the manufactured home companies have a modular home option, I know Clayton does.

You would need to hire a leak detection company to find out.