If they were to sell it on the market at a higher price and interest rate the numbers would not pencil out for me to rent it out. 

Lower income areas tend to see lower rents, slower rent growth (Outside of initial renovation).And, if you are taking out commercial loans, there will be a DSCR test along with the appraisal and LTV.  

As a broad rule of thumb, the 50% Rule for SFRs states that about half of the rent will go to non-mortgage expenses.

Keep in mind that when you are renting your place, these websites don't always talk to each other so check to see if your property shows up in a particular website. 

Can you convert it back to an Airbnb for additional income and use the proposed rents to offset the mortgage so you can buy your new home? 

Yardi tracks vacancy and asking rents at each property over 50 units on a monthly, quarterly and annual basis.

If it's a rental, you can structure the loan so that the monthly PI is lower than the rent income.

You might want to consider negotiating with the seller to resolve these issues as part of the deal.House Hacking: Living in one unit and renting out the others can be a great way to cover your mortgage and build equity.

Rent it and once your comfortable you can move one on the 2 property.

Do you mean completely turnkey and new or renovated and rent-ready?