And it doesn't seem to spoil the charm for couples on a romantic getaway.We've been able to raise the nightly rate 2-3x with better occupancy. 

That is tight leverage for an investment 2nd position loan.A private investor might be willing to do it, it's not going to be cheap at all & will be short-term money & will not be a line of credit to take out at your liking.What is your rate on the 1st?

Or a seller finance calculator showing the monthly payment based on negotiated price, interest rate, down payment, etc.

Be sure that you are honest from the jump, your estimated rate are only as good as the info you give them.

Average rental rates, vacancies, competition, growth, appreciation, etc..Ive heard of scrolling through Zillow and collecting information by looking at properties for sale/rent but was wondering if there is a site where all of this information is easily accessible or any ideas for better ways to go about it.Thanks in advance!

Was fortunate enough to lease for higher than expected rental rates.

The interest rate on a HELOC or Heloan may be better than the personal loan. 

What they will offer you is an appliance package, or closing cost help, or a low fixed rate loan. 

Private Money or Hard Money LoanHow it works: Short-term loans from private or hard money lenders to purchase the lot and finance the construction.Benefits: Easier approval and faster processing, focusing on the property value rather than your income.Downside: Higher interest rates and shorter loan terms (typically 6-18 months).

The amount of equity I call pull is less than the cash I have but not significantly less.When doing this analysis it struck me that it may not be worth using a HELOC for the simple fact that the interest rate is ~9%* while the funds in my high yield account are only yielding ~5%*.