This can be a great way to mitigate risk and stress of stock market volatility knowing you have steady income outside the market that should not only be minimally impact by temporary market recessions/corrections but that should see steady increases throughout your retirement. 

Being self employed brings on a whole new set of risks emotions worries and when it goes good feeling of success. 

I agree that mathematically your approach may make more sense but, speaking only for myself, debt management is an emotional issue.

In a warm belt state maybe heaters can be placed outside and a temporary structure put in for extra seating when temp is 50's for a month or two.

A good investor uses logic, not emotion to make decisions.

@Michael Hopkins if you are going to offers on a SF, you are up against emotional buyers (homeowners) and you aren't going to get the deal at a price that you like (i.e. a price that makes sense) ....

Be aware that if someone has an Emotional Support Animal or Service Animal, you cannot charge any deposit or added rent.

I don't think you want to advertise month-to-month, because you may attract someone who only needs temporary housing.

Very often such an owner is unwilling to sell in part or whole because they are mentally/emotionally unable to adjust to changes in their routine, in their bodies and in their mental acuity. 

I have heard others state they just like to experience different places, they are building and need a temporary place, or they just got divorced and are looking for temporary housing until they can rebuild credit and then buy, all valid reasons but most likely shorter term.