Except that you will be required to get a loan for $200k or put another $200k from your pocket in to the deal.

They wouldn't be able to get a mortgage, but would have to do some kind of SBA loan or other commercial loan for the business with the properties as part of the business.

You would have to check the loan terms.

and also, should I be recording the owner finance loan in any other place besides the properties tab? 

I focus heavily on the sell side and on the buy side only work with high net worth individuals so the newbie wanting a 400k multifamily with an FHA loan probably isn't for me. 

I concur with @Joe Davis and do the same with my company, however I refer other loan types outside of Transactional Funding loans to others.

It’s a bonus if the bank offering the HELOC also handles BRRR loans — they’ll be more flexible and accommodating when it’s time to pay off the HELOC with a new loan!

The appraisal came in at $245K, but they are only loaning me 70% of the ARV.

They close hundreds of loans a month and charge you for any hold up on their end.

In 30 years the balloon payment is due to the seller and that's when the taxes are due.Coupling a monetization loan to an installment sale accomplishes the same thing but puts cash in the sellers hands that can be re-invested.