I’m looking for ideas of how to do this, and any advice on how to protect my primary property along with paying low taxes. 

Last thing, I would strongly consider consulting with a knowledgeable property manager or attorney once you have a copy of the current lease and all of the facts.

Property taxes creep up, exterior repairs , and a brand new HVAC last year wiped out $11k of reserves.

The 15% tax hit is a one time expense, versus 4.3% is annual interest.

The house has appraised for $335k, my hard money note is for $242k, and I'm looking at only about $15k out once closing costs, taxes, and insurance are accounted for.

For instance, Berea is a charming college town, but the combination of local taxes and less favorable price-to-rent ratios makes it less appealing for investment compared to other areas in the state.Agree here! 

The big pro that sticks out to me in Birmingham is the tax rate. 

Using Zelle, CashApp, etc. makes your taxes harder and it's all not in a system.

even if its interest only, id want to pay down principal here and there. seems like sellers would offer this interest only route so they have 0 capital gains tax, but id rather pay down a bit of principal in 7yrs. i see its not required but it should allow for principal paydown in promissary note3) any general advice to look out for on seller financing?

One time when I bought on owner financing, I totally forgot that I didn't have property taxes included in my interest-only payments to the seller.