@Brian Beck LOTS of solid advice for sure as I scroll through the comments. I will share mine as well. With any investment there is YOUR risk tolerance. Each person has their own level. Each investment pings that tolerance. Here are options available for your review:
-With the HELOC there is a method called 'debt arbitrage.' The money from the HELOC is used to purchase something greater than the payment of the HELOC. The difference between those two numbers (the delta) is yours to reinvest. HELOC is 3% Investment 10%, you keep the difference.
-Private lending. You get to set the percent of return and the duration. First position as a guarantee. Monthly payments or capital and interest at the end. Points if you desire.
-Syndication. Large MF invested as a Limited Partner with a set return for typically a 5 year hold.
-Buying a portfolio of properties with property management in place.
In the end, be comfortable with your choice from the numbers you run (underwriting) and the risk tolerance you have.