LOL.Yes I am an appraiser which is why I chuckle with my advice.Figuring ARV is not rocket science, but it does require access to meaningful sources of data for the best results.Appraisers have access and are the best choice.Realtors have access and are the second best choice.Being your own appraiser trumps all choices.Being a good appraiser includes compiling as many sources of data as possible, this could be doing your own research, then supplementing it with an appraiser and a realtor.

To date, that is the only rental property that we have but we've decided that moving forward we want to start growing our portfolio with the goal of supplementing our income, growing a business and eventually, obtaining financial freedom. 

I started out using my license as a supplemental form of income as well.

And option three is you are upfront with them and price the unit accordingly, accounting for anticipated electric costs for running supplemental space heaters on the tenant's dime.

To supplement my 401k, IRA, and brokerage accounts, I want to use real estate as an additional vehicle to invest in.To start, I'm currently looking in Northern Indiana (e.g.

new unvented gas heaters advertise that they are for part-time, supplemental heat only for that reason.

I am a software engineering manager by trade but looking to get into real estate as supplemental income. 

My business policy is to not devalue my investments by supplementing tenants rent through charging under market.

I got this from an attorney that I trust.Also the IRS has this to say about it:Here are some tips from the IRS about vacation rentals.You usually report rental income and deductible rental expenses on Schedule E, Supplemental Income and Loss.https://www.irs.gov/newsroom/renting-your-vacation...

The tenants rent payment will supplement their mortgage.