I would look at the DSCR loan as the first option.By the way, I suspect you are going to be disappointed by any refi appraisals   ADUs typically appraise poorly   JADUs can lower the property value Vs having the space as part of the primary unit.  

Use a home equity loan (fixed debt) instead of a HELOC (variable equity) and build an additional unit you can rent out in your own backyard.

Conventional Loan

Lastly, land development requires solid planning and capital, so getting the right development loan with flexible terms will be vital for success.

One thing that may work is doing a Subject to Existing Financing deal where you will buy the property from someone but not payoff their loan.

Last minute they changed the deal to a mortgagee loan and cut the SOW from $65,000 to $40,000.

Since I’m holding these properties for the long term (30-year loans), I’ll have fully paid-off assets around the same time I’d traditionally start withdrawing from my 401(k).

Some lenders do a periodic search of ownership records of all properties in their loan portfolio.  

Last property I bought had 8-9 offers.New York has a lot of downpayment assistance grants and loans. 

Were seeing projections that new construction is going to make up a much higher percentage of loans by the end of this year.