My goal is to house hack a SF home and rent out the other rooms.

The tenants that you get, offset what you would normally pay, so it's a great set-up with less risk than having 2 mortgages to pay for if you lived in a home and rented out a 2nd home when you start this REI journey.In Gilroy, you will get appreciation, and you should be able to rent out rooms at a good price point. 

I like to overestimate a bit to ensure I'll have some wiggle room should it take longer than anticipated.

Typical rent for single room is $500 and for families anywhere between $1100 and $1800 depending on rooms and bathrooms and whatnot.

I am not an expert in the Boston market, but some potential ideas could be rent by the room, multifamily, or STR.

However, when I pull the property records from the County, the County lists the property as a 3 BR (the 3rd BR has to be the attic - there is no other suitable room). 

We have a flip project going on in Atlanta  and now we've been thinking thinking about house hacking something around ($250k) and finally getting out of our apartment, we already have a close friend who would rent out the room/apt/duplex but we also really want to get into one of our local rental markets and purchase a cash flowing SFH since they are so cheap and its on an army base (PP:$100K Rent:$1,200) (we would do both of these conventional) so my question is, should I purchase the cheaper rental first and get it cash flowing then go onto either buying a home or buying a home to house hack?

Some people rent out rooms in their single family home, but you want a family.

I currently own 2 single family rentals in casa grande and my fiance also owns a single family rental in casa grande on her own.

We have a flip project going on in Atlanta and now we've been thinking thinking about house hacking something around ($250k) and finally getting out of our apartment, we already have a close friend who would rent out the room/apt/duplex but we also really want to get into one of our local rental markets and purchase a cash flowing SFH since they are so cheap and its on an army base (PP:$100K Rent:$1,200) (we would do both of these conventional) so my question is, should I purchase the cheaper rental first and get it cash flowing then go onto either buying a home or buying a home to house hack?