Syndications as an LP is the most passive vehicle I'm aware of.

All the COVID-related financing changes may have just made this even more difficult to boot.I like notes as an investment vehicle as well...may get into those after the move.

Location refers to the macro area (population growth, job growth, vehicles per day, entry and exit points, signage, etc).

With that in mind, it won't make sense to utilize an IRA for your rental activities.A lot of my clients use IRAs as lending vehicles.

The bigger issue I see is people smoking pot getting behind the wheel of a vehicle impaired.

If your "business" is generating passive income such as rentals, interest or dividends, then no, that is not self-employment income capable of sponsoring a Solo 401(k)Of course, the Solo 401(k), which makes a great self-directed investing vehicle, is only eligible to owner-only businesses with no full time employees working more than 1,000 hours per year.  

How do you handle tenants doing drugsHow do you handle noise complaintsHow do you handle vehicle violationsHow do you keep a tenant long term?

Years ago when I lived in Fl. mobile homes had the same title as vehicles.

Condition and age of vehicles on road? 

The IRA's LLC are nice vehicle, but you have to keep an arms length distance to prevent self-dealing or engaging in prohibited transactions.