Or number of occupants?  

You've probably already considered this, but why not buy it as your new primary residence, get the better terms of an owner occupant mortgage, live there for 12 months and then re-evaluate? 

Another option is to split the cost based on the number of occupants in each unit but this also means you'll need to adjust the charges as tenants move in/out, so it requires more work and I wouldn't recommend it.

Please give me constructive advice on investing in single family homes.  5% down to buy a single family home as an owner occupant is pretty typical.

Is a  non occupant  co borrower  ( like a  relative/ parent ) an option ?

My advice is to sell, but give the current occupant an unofficial right of first refusal.

I recommend a couple of options to get you the highest return and the quickest occupancy:1. 

Bottom line: now more than ever, NOBODY knows what the market will look like in the future, so if your plan depends on hitting an ARV, you're making a gamble.I didn't run all your numbers, but at 11%+ interest on your current loan, I can't imagine that your current loan isn't a significant problem to your numbers...If it's in the right area, turning it into a STR could work (though, that comes with its own challenges and risks, and the STR market is also getting very difficult right now).Can you move into the property, refi into an owner occupant 30 yr fixed, and house hack?

To be honest, most investor clients are not nearly as loyal as regular home owner occupant types.  

I think demand for rentals will only increase over the next 24 months, which would normally increase rent rates and occupancy levels.