Several times I've changed the purchase price, repair estimated costs, as well as financing details (interest only payment vs. not, amortization over 30 years vs. 1year for conventional vs. hard money, etc.) and the ROI still hasn't went positive.

With conventional;For a SFR you can do a max LTV of 75% to cash out.For a MFR you can get an LTV of 70% for a cash out. 

5% Is the conventional route.

We've got over a dozen of properties loaned with conventional mortgages and at this point it's getting more difficult to get advantageous rates for additional properties.

My concern is how do I have the personal protection of an LLC if I essentially cannot get conventional financing or transfer the title after the purchase?

I work closely with on of the branch managers in Queens, New York.They've done 5% down conventional loans for house-hack clients of mine and can also finance condo deals. 

I'm confused by your question...is the funding you have that's not hard money conventional financing?

I made it all the way to the appraisal....paid $500 for it, and was told that I couldn't get a conventional loan until April 2020.

I'm curious of anyone has any perspective on getting a hard money loan for the build and cash out refinancing the DADU with a conventional mortgage? 

Commercial loans are different from conventional in several ways:1) They are typically not fixed rate for the entire term of the loan.