Commercial Loan Underwriting Problem

[Account Closed]

How does commercial underwrites calculate DSCR with no direct way to verify NOI? 

I want to purchase an off-market, single tenant, and vacant bank building but there is no rent roll. It was originally built by the bank that occupied it (no rent paid), then was bought out by the city for street expansion and never leased out. The road upgrade ended up not impacting the building and the city is planning on offloading the property.

How does commercial underwrites calculate DSCR with no direct verifiable NOI? I could follow-up with the lease offers the city has received, which has been numerous, and sign an "intent to lease agreement" or something. Is my only options to pay all cash or owner finance?  Really in a tight spot here... Thank you for your concern.