This refi strategy was to reduce the rate and improve cash flow.

It allows you to avoid the $7-12k cost associated with hard money loans (HML), which can improve your total ROI and cash-on-cash return.

Agreed but improving..Not for STR though :) 

Next came what I would call 'land speculation' (SDIRA purchases unimproved parcel and subdivides or does site improvements, then cashes out) followed by a distant last place - rental investment.

Buy a 2-4 unit with either 3.5% down or 5% down, make valuable improvements that will increase equity, and in two years time consider selling.

You also don't want to over-improve but if you're keeping it as a rental you don't want to have to replace them within the first few years either. 

This can mean some improvements, new and more resilient tenants, or just some attitude adjustments.

I'm willing to hold onto this house for another year or two to see if it improves. 

I'm looking to deduct HELOC interest for costs related to making improvements on a primary home that is also used as a rental.

Bob, what type of improvements did you have to make?