We have put a day bed with a twin trundle in huge primary bedrooms to fill some extra dead space, but this is usually only done in very large homes where 3 + families are likely booking. 

If I were to BRRRR a quadplex, when it comes to refinancing, would I be able to structure the loan as my primary residence (house hack it).

Just to confirm, the HELOC would be against your primary and used to improve the same property--right? 

Here are our mortgages and a snapshot of each one1) Primary residence: 6.2%, $2,240/month (29 years left)2)First rental: 3.2%, $1,440/month ($500 CF, 10 years left)3) Second rental: 7.2%, $2,100/month ($300 CF, 30 years left)4) Save another 20% for another investment home.

We currently live in our primary residence and have the intent of moving out in 1.5 years and make it a short term rental once we move out.

What Jaron is referring to is the current forgiveness of up to 250k in capital gains per spouse when selling a primary residence that has been owner occupied for 2 of the last 5 years.

Hi,My wife and I moved into our current place about a year ago, and converted our prior primary residence into a long-term rental.

Purchase price: $235,000 Cash invested: $39,000 Bought as a primary residence, once we moved out we have begun renting both sides.

Your next cheapest option would be to buy a multi-family as your primary home.  

This will serve as my primary residence and I'm hoping to rent out the other 3 units.