In my experience the portable heat pumps do not do as well as ductless in cold weather and I supplement the portable heat pumps with a construction heater in my own home.

Speaking as a US urban homeowner, supplementing our retirement income by running 2 Airbnb units in our 2-family home...The "hotel industry" includes a ton of low-paid workers. 

My spouse and I are interested buying and holding single families and small multi-families to supplement our full time incomes and build our way to financial independence. 

Afterward, if you have the time and patience to write letters and build an email list and whatever, you can do that to supplement your marketing efforts.Feel free to contact me if you want more information! 

Which would be an ideal retirement supplement income on top of our other investments.

@Lieren SchuetteBrokerage account can supplement standard checking and savings accounts.

After buying 10 the average UMC folk should be able to supplement most their income.

SSI stands for "Supplemental" Security Income, ...as in, additional income added to your retirement income. 

Have you signed up for Tom Brady's nutrition & exercises TB12 program?

They make diddly-squat on it BUT when slow, it supplements their inspectors, is super easy, quick, and helps for retention in the slow periods.