I do see lots of self storage and warehouses going up, so my default assumption would be that the old shopping malls do NOT trade for less than build cost, but it's possible that the marketplace is not perfectly efficient. 

HELOCs are fine, but keep in mind that you really only want to use 50 percent of less (each) of your available equity just so you aren't creating a problem that you can't solve later if the value of your personal residences fluctuates.If you both have W2 jobs though, have you looked into getting qualified together and just getting a loan, 10 percent down each?

While most of his experience is with new construction rather than remodels, he’s already given me a few pointers and is looking into potential referrals for me.

Or are you actually talking to a bank about buying the note so you can see the notes and credit on the owner of the property?

What's a "snowball" called when you end up with less money than you started?

Appraisals came back awesome my credit score came back 720.

Some lenders will allow you to go off the appraised value with less than 6 month seasoning, if you did work to the property like you did.

Far more costly to transfer property at a later point than simply purchase in an LLC on day one.

Solar has an energy credit and Starlink is deductible as business expense. 

Always good to have more information in an intro than just a "hello" so we can point you in the right direction.