$300k cash, questions about HELOC multi-family buying process

[Ryan Jones]

My wife & I have $300k cash and are buying a $500k new construction primary home for ourselves set to be completed in November. I had planned on doing a $300k downpayment for it, getting a mortgage for $200k, and then opening a HELOC (let's say it's $225k allotted) to buy a cash-flowing multiplex. Let's hypothetically say purchase a multi-unit (over 4 units) at $700k purchase price with 25% downpayment and some room for cosmetic repairs and closing costs. (At that rate, should I create an LLC and loan the HELOC to it, and then get a commercial mortgage loan through the LLC)? I have also read about buying lower priced $50k properties all cash but that seems to lose the value of leverage and thus give smaller cash flows.

I've been reading a lot about HELOCs and from advice I'm reading, I gather to really only use a HELOC as a quick temporary purchase vehicle since technically the lender could call the balance due at anytime. But if I buy a multi-unit property that isn't a fixer upper whereby the ARV wouldn't be much higher than the purchase price, refinancing to a mortgage on it WOULDN'T be able to pay my HELOC back all the way. Are people only using HELOCS whereby you plan on definitely having a higher property value after purchase (meaning you can only buy fixer uppers)?

In my financial situation, can I quit w-2 income and do something pretty strong with $300k to invest full time to grow and grow?   Basically - what would you do in my situation?