@Steve R.

Zoning dept told me the house we wanted to convert into a duplex, is zoned as R-4, and we cannot separate floors.

@Matt R.

I would like to continue investing in the area using the BRRRR method and buy and hold after this house hack. 

As I've gathered, the terminology and methods have changed somewhat over the years. 

Either way, the method of payment will not change the taxability of the repairs.  

If your realtor doesn't have a sophisticated system for querying the MLS a lower-tech method is to have the agent do a full CSV dump of the MLS for SFR and send it to you after stripping out the non-public data columns. 

@Albertinny Colin yeah, you can kind of see where all of these are going but the ENTIRE point of the BRRRR method is to reduce the out of pocket expense you have.  

I'm not sure that picking just one strategy is a good method, similar to what @Joe Villeneuve said.

This could get messy.....I found a better method to be this: ask for an invoice for each phase (or so) of work...i.e Demo/Foundation, then Framing, rough, then Electrical/Plumbing /HVAC.