@Eric Wagner "Is this prudent/risky?" Yes and yes. It is risky, but so is getting a mortgage on an investment property. You will most likely have to personally guarantee any investment loan, and your primary home is part of the backing of your personal guarantee. Point being that really anyway you slice it, there's some risk to your primary home if everything goes sideways. (LLC is unlikely to help also, unless it has a significant track record and enough capitalization to not require the personal guarantee).
BTW, I'm in a similar situation. I have a heloc and verbal funding for an investment, when I find one that fits my criteria.
The question I'm asking myself is, "How do I mitigate the risk to my primary home if/when I leverage to purchase an investment property?".
For me that means being able to cover all payments for the short term, ≤ 6 months, (mortgage, investment property mortgage, heloc, etc) with liquid reserves. (Be cognizant that CC, heloc, LOC, etc, can be frozen at the whim of the bank. If you are significantly leveraged and need to access cash from debt, that can make you look risky to the bank, which can then freeze the funds you might have been counting on. Ask me how I know...)
Long term, that means being able to cover the house and the heloc payments from W2.
That's my thoughts. I hope it's helpful!