I don't know the CO law.A duplex by nature is multi-family.

Of course as nature of things the community of investors in my area that are investing in the US is small and no united network of investors exists.Couple of days back a large conference of investors took place and I mingled with everybody and handed out business cards and managed to assemble 20+- investors to open a REIA. 

You have to adapt to the new era of higher cost of capital, lower supply, population changes, natural disasters, etc.  

The truth is that any data or track record can be interpreted in multiple ways, and each sponsor will naturally present their results in the best possible light.

Tulum grew from 28,000 to 49,000, received an airport in December 2023, and the greater area is now projected to reach 410,000 by 2035.I am now interested in setting up some cash flow concepts on certain plots of land with natural features and strategic locations.

The previous owners invested over $12M into building it between 2009-2012 but then left it vacant for years, allowing it to naturally age.

In general, a turnkey can be a great way to avoid conflicts with those rules because of the highly passive nature of the investment. 

✅ Low operating costs✅ Low crime rate✅ Low risk of a natural disaster✅ Sufficient population to have economic stability, major highways, and a major airport.

Can you please elaborate why the business activity nature of STR will be treated differently due to part of the property being primary residence and under which rules?

Based on what I remember, it gets even more complicated if the 401k is from a previous employer.In your case, since Fidelity is declining the account due to the nature of the retirement funds, one option might be to consider rolling over a portion of your 401k into a self-directed IRA, which typically offers more flexibility.