This should be your primary concern.

Who has closed a subto deal for a primary residence?

I don't know your living situation but if your paying x,xxx for rent or a mortgage and instead by living in one side and renting out the other you will be paying y,yyy instead and y is less then x that's great, especially if you can rent out your primary residence and make income there too. 

The projects discussed on this string are from a previous company called Financial Attunement, where Neal was a junior partner, and a senior partner was CEO of that company and primary decision-maker.

my condolences on your recent lost.there are a few ways you can do this, as mentioned above you can take a heloc on your primary residence which will give you a second mortgage, first mortgage payment wont be impacted. you can do cash out refinance which will give you one mortgage and payment. it will pay the old mortgage and give you money in your pocket to pay for the rehab.or you can do a renovation refinance which is similar to cash out refinance but we would contractor involved  as part of the refinancing and they are paid through the loan

I would not be living in any of the units as I already have primary residence in town.

I got approved for a HELOAN on my primary property but not sure if I should take the loan to just use as “leverage/reserves” to show the HML and get funded.

The primary issue is that building small unit in a single count is some of the most expensive development.In addition, in most jurisdictions the primary unit will become rent controlled (assuming more than 15 years old).  

At this point I was still doing nationwide Google Ads as my primary source of marketing.

Best advice to you would be to use that VA loan as many times as you can and buy primary residences for a year, rent them out and then buy something else with the VA!