How picky do you need to be with #s when house hacking?

[Adrielle Tecklenburg]

Hi all! My husband and I live in the central valley of CA and are planning to purchase a house hack in - hopefully - early 2020. It sounds like in order for an investment to be a good deal, we need to have double our mortgage and then some in rental income? We're planning to buy a SFH with one or two units in the back. If we're able to find a deal with two units, we should have our mortgage payment covered by those rents (we'll be using a VA loan). The SFH would probably rent for about 80-90% of whatever our mortgage payment ends up being once we move out (maybe more with improvements, but I'm trying to be conservative with my guesstimates). My question is, with these numbers, will we actually be able to get ahead financially? The more I learn about evaluating the numbers on a deal, the more I'm worried that we won't actually be able to save that extra $ we think we'll be able to, from having the rental income to cover the monthly PITI.

Due to our family circumstances, moving to a cheaper cost of living area won't be an option until 2030 at the earliest. We were hoping a house hack like I've described would allow us to save up really aggressively to start doing out-of-state rentals, but I'm concerned that we'll just break even compared to where we are now.

Thoughts and advice are appreciated!