, (b) products with variable rates and (c) loans for non-income producing assets/ liabilities (depending on the terms).If you can swing the student loan payments, and the rate and terms aren't too crazy, I would imagine securing a nice income property with a low fixed-rate mortgage might be a good way to go.Since the principal on my student debt, for example, is on the low side with a manageable interest rate, I just make the monthly payment and focus my resources on other endeavors--the primary endeavor, at the moment, being rental real estate acquisition.

The HELOC is likely variable and up above 9% if not more, but the conventional deal, depending upon when you got it, might be at an incredible rate and you might not want to take that out.

@Wendy Schultz is correct, 18-20% of purchase price is a good rule of thumb for gross revenue in the Smokies, though of course there are always variables involved just like with any market.  

What major factors would you be looking at on HELOC - start up costs, ongoing costs, fixed vs variable rate, other fees?

In my experience, the thing that's most variable is the class of tenant and applicants.

Goal seek is manual based on a single variable, Data Table will automate the purchase price output based on two variable inputs.

Pricing sofware/AirDnA are good points, but take too many other variables into account (Vacasa/etc just putting heads in beds)...ensure you are looking at similar properties in the area and pricing at or just below their price. 

I made some pretty conservative assumptions, 10% vacancy rate, average rent, decent variable expenses to save for each month and this deal still cashflows pretty heavy and is about a 20-30% CoC return...

You have a lot of variables here and are relying on a best case scenario for things to work.

Under such circumstances, they will incur the expense, yet the property managers and contractors will not give them a break for their opportunity cost.I guess what I'm saying is, is opportunity cost really a variable in anything after the decision has been made to pursue the project?