I've seen some as low as 6k and as much as 14k annually.

They should be able to determine the COC, annualized return, estimated ARV of a BRRRR, accurate rent comps and more.

We have an upcoming meeting with them to see how we can extend the loan a few more years to make the total monthly payment including installments for the annual property tax bill, which we’ve had to pay for them this year since they were late the last couple years and had to pay interest to the county. 

Investors in these type deals look for say 12 - 14% annualized return.  

I'm still struggling to get my first AirBnB but values are rising, gross annual yield is mainly above 10%

The quotes were only a few hundred dollars extra annually.

Their pro formas felt optimistic with providing 6% annual appreciation and property management that is only about 6% of rent so I take it with a grain of salt (they offer their own property management services but it has terrible reviews on Yelp so I would probably go with someone else). 

With my rentals generating around $46K net annually, I’m hesitant to take on a long-term loan just to keep payments lower, so I’m leaning towards a HELOC.

Do you know if there is a service, monthly or annual fee for opening one of these accounts? 

This can save thousands annually.