Don't get me wrong, I feel like a good PM is invaluable and have no issues paying one their 10% to properly manage my property and take away my headaches. 

Issue is he is paying 750$ a month for the 3br/1ba unit.  

This creates two loan payments ($100,000 of equity and $300,000 on the new mortgage).Key NumbersHome Equity Loan Interest Rate: 6%Mortgage Interest Rate: 7%Rental Income: $3,000 per monthExpenses (management, taxes, insurance, maintenance): $800 per monthIncome and ExpensesMonthly Rental Income: $3,000Monthly Expenses: $800Monthly Mortgage Payment: $2,000ExplanationThe investor earns $3,000 in rent each month.They pay $2,000 on the investment property mortgage and $800 on other expenses.This leaves $200 profit each month or $2,400 per year.However, you have to pay $6,000 interest on the equity borrowed.This leaves you with an annual loss of $3,600.While the rental property generates positive monthly income, the interest cost of borrowing the initial $100,000 results in an overall annual loss.

This topic comes up with more expensive fix and flip courses where you have to determine the timing of the deduction and when the course was taken when folks are transitioning from their W-2 jobs.  

You pay them 10% (of nightly rate plus any additional cleaning or pet fees) to basically manage your listing and your calendar.

It might help pay for your expenses if you house hack but I bet the number of markets a 3.5% down payment is cash flowing has shrunk significantly over the past 2 years.

It also gives the tenant time to arrange for 1st month's rent, if they choose to not pay it along with the security deposit. 

Are you going to pay a company or do it yourself?

Which would leave a balance on the heloc for me to pay off.

You have to pay to  take it off and pay to put it back on.