It does come down to your goals, your time to allocate, your business sense, your ability to bring or raise capital, and what you are trying to accomplish.I am personally not a fan of short term rentals, as it appears regulations in many cities keep making it harder.

Ensure your attorney is well-versed in lending regulations and set up a strong legal framework.

@Anibal Mijangos - Rental arbitrage is a great business wherever you can find below-market rental units and favorable STR regulations in strong Airbnb markets. 

Careful regulation and oversight are needed to ensure that such programs truly benefit those they aim to help without unintended negative consequences.

Regulating rent rates creates less inventory and higher prices.

@Eden Meng contact your Solo 401k administrator regarding regulations regarding leasing  mid term and long term rental properties.They should provide guidance regarding prohibited transactions.

Rent-by-the-Room (Long-Term)If local regulations allow it, renting out units by the room might generate more income than traditional long-term leases.

Temperature control:  It's always naturally cooler downstairs, and in the heights of summer and winter, I just cannot get the temperature regulated for both me and my tenant to where we're both comfortable. 

Byzantine planning and landlording regulations.

Consider exploring financing options like FHA loans or conventional loans with low down payments, understanding local regulations, and conducting market research to ensure you can cover your costs.