But when I say full gut and rehab I'm talking: taring everything down to the studs, updating plumbing and electrical throughout, probably upgrading the panel, adding duct work for heating and cooling, new mechanicals (boiler, A/C, etc) , hardwood floors, new kitchen, new dry wall and insulation, paint, finish work, etc.

Two areas where I build a safety margin are cash on hand (I want to be able to make   x  number of payments with no correlated income) and spread (the difference between rents and all expected expenses ie expected cash flow--the higher this number is the easier it becomes to make the debt payments)So for example say I am looking at a duplex for 100K and I have 50K in cash. 

we have a small STR duplex maybe 100 yards from the beach that has an average rent of ~$13,500/month (more in summer and less in winter).  

Working on a duplex deal for another investor and I'm thrilled there's a responsive agent!

The second had the garage door removed fresh drywall on the walls and ladders sitting in the garage.

Sometimes we just trade information: "That title isn't clear, I saw bad cracking on the back wall of the foundation of that place, FYI, that one was just postponed."

I'm based in CA and just purchased two turn-key duplexes in the Milwaukee area.  

Funny I sold a duplex in Chicago for this exact same reason.

We'd like to use her VA loan when she becomes eligible to house hack but she isn't super interested in the duplex/triplex/quadplexes we've found in that area... they're generally in neighborhoods we would never feel safe living in.

Have you thought about using your VA Loan to get into a multi family property such as a duplex or even a fourplex?