Sec 199A deduction for Rental Real Estate Question

[Rob K.]

So for purpose of the Safe Harbor Rule for Rental property owners taking the Section 199a "QBI deduction", my understanding is that starting this year you document that you spent 250+ hours for your "rental real estate enterprise". It is also stated that commercial and residential real estate are not supposed to be part of the same enterprise. 

Where does mixed use, both residential and commercial rental property fit within this notion of an enterprise? Say you have residential properties within an enterprise and commercial properties within an enterprise for purpose of aggregation in addition to your mixed use property. How do you treat it? I would think it would be logical to split this property between the two enterprises but this might run afoul of the separate books and records requirement for each enterprise. Have any accountants out there looked at this issue? Thanks.