They also usually require "reserves" to refinance (most loans do at least). 

I've included an example below to help illustrate this.So different lenders have different rates (which do vary even for DSCR loans) but these are factors they all consider.See example below:DSCR < 1Principal + Interest = $1,700Taxes = $350, Insurance = $100, Association Dues = $50Total PITIA = $2200Rent = $2000DSCR = Rent/PITIA = 2000/2200 = 0.91Since the DSCR is 0.91, we know the expenses are greater than the income of the property.DSCR >1Principal + Interest = $1,500Taxes = $250, Insurance = $100, Association Dues = $25Total PITIA = $1875 Rent = $2300DSCR = Rent/PITIA = 2300/1875 = 1.23If a purchase, you also generally need reserves / savings to show you have 3-6 month payments of PITIA (principal / interest (mortgage payment), property taxes and insurance and HOA (if applicable).

I asked the underwriter to confirm the numbers.

Confirm their numbers are realistic by reaching out to other investors or brokers in the area; do your homework. 

It starts with a visual inspection and confirmation/denial. 

Criticizing others for their failure to do the same provides them self-justification for their confirmation bias.This is a common behavior pattern to justify many debatable decisions people make in life.

I would use a service such as vacationrentaldesk.com for this.A direct booking is no more risky than a booking through VRBO or Airbnb; they aren’t verifying identity, either.In fact, my own company has taken thousands of reservations over 19 years, and we don’t verify identity.  

We can assist in building the scope of work and even visit the property on occasions to get updated pictures/video and confirmation that some work is completed before the next draw, but we can't tie up our operational resources to projects that take more than a couple of weeks.

Along with connecting with governing body to confirm zoning and preliminary site plan. 

Depending on the exact location of your duplex, this could be an ideal opportunity to rent by the room, particularly given the area's demand from hospital systems and Case Western Reserve University students who are always on the lookout for housing.