It should simply be treated as a means to enhance the diversity of your portfolio.

Any programmable thermostat that has the ability to lock the screen with a pass code should work.

Without responding with respect to your zoning and what is allowed locally, I will discuss what is allowed on state level because i believe it will allow what you seek.In 2025 SB 1211 (Skinner) – Multi-Family goes into effect allows an ADU (I think it specifies detached but question if that is a requirement) for each legal non ADU unit up to 8 units.  

After the current tenants move out, I need to replace the carpet and pad. 

Right now, the one that has been catching my attention the most is the BRRRR method.

They passed the resolution.

The son lived with him, was a co-tenant on the lease, and was the main person making the rent payments.

The mother has continued to pay the property taxes and has kept them current.

100% you should chalk this up to a lesson learned and fix your process to make it better in the future.I tend to remind myself that your tenant is in a situation worse than yours. 

or not worth the extra money?