I think upwards of 40% depending on variables that a CPA can walk you through.

Not exactly, too many variables.

The HELOC would be a variable interest rate, correct?

@Alex Silang Yes, lenders typically consider Short-Term Rentals (STRs) riskier than Long-Term Rentals (LTRs) due to income variability, which leads to higher interest rates.

After contacting about 4 lenders, I am finally trying to choose between these two offers:Option #1: 200K at 10.5 % variable rate, 20-year draw periodOption#2: 138k at 7.6% variable rate, 10-year draw period.Which of these would be beneficial for a newbie investor like me.

Having trouble analyzing this deal as there are so many variables and I do not have the experiencing analyzing deals to make me feel comfortable taking the risk.Purchase price of the land would be $250,000 not including closing cost or fees, and construction for a new 3/2 home with an attached 1/1 ADU is estimated to cost around $300,000 - $400,000 finished.

They're variable rates so they'll go down when interest rates go back down.

-Tips for managing the HELOC and property finances effectively.Others have advised that a HELOC only makes sense for short term use, not long term due to it's variable rate and risk of over leveraging.

I know this, because I DO this, I have been variable/commission based for over 4 years now and I have a good real estate friendly CPA. 

Zipcodes don't work too well as they are large and contain many variable areas.