@Adam PippertFirst off - You want to see if you qualify for partial 121 exclusionSecond - a QOF does not eliminate the capital gains tax, it will only defer it. 

Make payments to the HELOC from time of purchasing to time of refinancing the property.Rehab the property,Season it for 6 months.Refinance - use 70% of the ARV to payback the HELOC (eliminating the payment).Then not having an issue refinancing because of being a co-signer on the HELOC?

Eliminate the outbidding situation. 3.

All the deferred tax is eliminated and our heirs get the properties tax free.   

You did not so that eliminated your opportunity to do a 1031.BUT...

By having the Tenant, Seller, and Buyer complete an estoppel, you eliminate these surprises.Some things it may include:1.

City planning,  development happening on a specific block, a new ordinance in a zip code, the sudden decision to eliminate STR -- so many factors come into play and you need to understand quite a bit about a market in order to make truly informed decisions (or rely on someone else who has already done the analysis and can tell you what fits your strategy/goals.

On a longer-term view, make sure to get this first property repaired, upgraded, and fully ready so that you can minimize or eliminate your CapEx expectations for the next five years while you then focus on another property.

This method virtually eliminates any risk of having a nightmare tenant and you still have all the benefits of long-term real estate investing.

You want to eliminate the "what do we do" questions by having it all spelled out. - Capability and experience of your partner is critical.