The interest calculations is where I'm having some difficulty.

There is an app you can download called EZ Calculators that may help you somewhat.  

Now this property is in a class C neighborhood with a calculated 11% cap rate estimated.

Quote from @Erick Pena: A "good" rental property is one that covers all expenses (mortgage, taxes, insurance, maintenance, property management fees, and any other costs) and still leave a surplus (commonly referred to as cash flow).Calculate cash flow as: Cash Flow = Rental Income − Operating Expenses − DebtThere's much more to it, but that's the basic idea.

Unless you are unknowledgable, my bet is you could make more from rent than sale, and still have the benefits of owning the original home while you go do something else.The 25K you have left in property will be netting you(gross) of $350 mo or 4200 per year.

And your calculation makes sense for a property that you plan to keep forever so to speak. 

I'll bet you a cup of coffee no one has working keys.

Kieran, the best bet here is to refinance with a DSCR loan.

I was wondering if anyone had any recommendations on how to calculate a relatively accurate 5 year rent growth for a market?

Here's a bit more in detail about how rates are calculated for DSCR loans:1.