I would keep the work very cosmetic, and I would enjoy the additional space and/or revenue from the unit without considering digging up, etc. 

For example, I would recommend touching base with local landlords in the market you're wanting to do section 8 investing in to get a feel for how the local section 8 office handles landlord/office relationships. 

Question- do I keep the heloc I have and just pay it down or do I get a heloc on the rental property to pay off current heloc and go forward with another property? 

Do you even want to keep the home in MN since you moved? 

However, I wouldn't keep my hope high.  

My portfolio consist of duplexes and single family homes, and one STR, however this will be my first renovation other than minor touch ups. 

Professor Brian Andrews would be an excellent connection for you if you can get in touch with him. 

Then keep doing it over and over again.

I'm experimenting with several small touches to see what impact they have.

See, I have "Truth-Tourette's" so I would admit this honest truth, take your info, your "buy-box" criteria and keep in touch for anything that comes through my team that seems a fit, THATS where it can work.