30 Income Amount Total Gross Monthly Rent $2,000 Fixed Landlord-Paid Expenses Amount Electricity $0 PMI $0 HOAs $0 Property Taxes $215 Water & Sewer $0 Garbage $0 Monthly Insurance $90 Other Monthly Expenses $0 Variable Landlord-Paid Expenses Amount Vacancy (%) 5% Capital Expenditures (%) 5% Repairs and Maintenance (%) 5% Property Management Fees (%) 9%

I don’t honk there is a best market it depends on a lot of variables and my best market might not be your best market and visa versus.

There are so many variables to your question but I always go 30 year fixed in recent times. 

If the numbers show that it is a good deal,  there are some variables here.

   I am paying off or refinancing everything that is at @ 8%+, or that is a variable interest that could shoot up soon, and adding as much 4-6% fixed rate debt as I can acquire.     

There are so many variables, it's hard to know what the outcome will be. 

It's also true that STR management fees can be brutal, and self management may be questionable if you're using your SDIRA to acquire the property.... plenty of variables at play! 

Some sponsors are using variable rate debt with a rate cap and trading prepayment penalty risk for interest rate risk (both are risks).A case can be made for diversifying between fixed and variable rate debt (prepayment vs interest rate risk) across a portfolio.

When they first decommissioned the base, there was a fair amount of flipping of old PMQs going on, but I'm sure that's all done now.If you plan to borrow from family members treat it like any other private lender - have a loan document drawn-up with the amortization/payment schedule, interest rate (& whether it is fixed or variable), prepayment options, etc.

It is becoming apparent that a per sf price has many more variables than build price e.g excavation as Kristine highlighted.