.$130k debt on home including HELOC,  monthly mortgage & HELOC $1,155 month.

The opportunity cost (i.e. investing the initial costs + the savings from renting each month, into an index fund) seems to be substantial even with the tax advantages of owning a home.

It was probably close to zero per month.

So renting on the first year is somewhat comparable cost wise but as soon as it's longer than a year, owning will have a much bigger upside than renting.  

Are you looking into getting a cost segregation study on your property and wondering what benefits the study may provide and how much it will cost?

Then I would get a bridge loan (assuming each is above $100k purchase) and put $25k down on each one, get the lender to finance the loan for 12 months and give you 80-90% consruction costs then when complete refinance to a DSCR.

I aim to refinance within six months, ideally recapturing most of my HELOC funds in the process. 

In either case it is great practice to account for property mgmt costs.

Can you speak on how you source granite slabs cost effectively?

Unless the balance is low, you'll likely recover the refi costs in a year or so.