You should consider private money!

And as far as legal—an attorney becomes essential once you're ready to finalize terms with either an HML or private lender to make sure everything’s secure.Hope this helps!

or3) If I convert the partnership interest into a private UPREIT, then I trigger tax if/when I sell the Shares in the REIT?

You could get a loan from a local bank or private lender to fund it

If it is a private money/ commercial style  lender, it is a relatively simple process.

If we can't get an address to either party to mail a certified letter then a private investigator must be hired to locate them. 

Or should I get a private mailbox in Oregon and use that?

Establish an emergency fund and target stable long-term rentals or short-term rentals in markets you understand.House hacking or private lending can offer alternative entry points depending on your risk tolerance and hands-on involvement.

with private and HML  the deal is done all at once.. 

Begin by targeting distressed properties in gentrifying neighborhoods, securing financing through hard money lenders or private investors, and focusing on cost-effective renovations.