Those factors can jack up that $80k revenue real quick

Yes, you pay interest whether it's in use or not, but the downsides of a HELOC outweigh that factor, in my opinion.

Building one will cost you about $200-$300 a sq/ft so be sure to factor in those costs as well.Renting by the room will probably bring the most cash flow, but one has to be alright with sharing a space with multiple people in exchange for more money.Good luck getting started!

So multiple factors.

Factors that may help - sold off market, showing rental history of the purchase before and after, if you have a history of buying long term rentals.

It depends on so many factors.

But the numbers vary lender to lender and some will make allow for other compensating factors to offset low population / rural numbers.

Having multiple deals going on shouldn't be an issue for most lenders as long as your DTI and other qualifying factors allow for it.

The factors that add to strong appreciation also benefit liquidity.  

There are so many other factors that impact the final price that the square footage of the property is dwarfed by them - beds, baths, age, style, condition, acreage, garage, basement, HVAC, etc, etc, etc.