Hey Jared! As already mentioned, trying to refinance into a investment loan might not be the most beneficial. Other than wanting to buy another property, you would need a concrete reason for not living in the property for one year. In addition, the cost to cash-out refinance an investment property at 80 LTV probably would be beyond ATR/QM limits. Unfortunately, a cash-out refinance as an investment industry-wide would not be at 85 LTV. When using primary residence loans, you are sadly restricted with how quickly you would be able to scale.
My initial thoughts: What type of property would you be looking to buy as a primary residence? If you have a justifiable reason for buying a new primary, then it may be possible. I would not recommend refinancing that 4-unit at all. As I mentioned before, the cost to do so would be extreme and your interest rate would be higher. You don't need to refinance out of the primary residence loan to buy another primary, but the other seasoning applies.