Determining ARV of Small Multi-Unit (1-4) with No Comps

[Isaiah Lynn]

I have an off market duplex in a rural area that I'm considering purchasing. It needs some renovation - around $75K. I'm acquiring the property through a combination of personal money, private money, and hard money. 

Exit strategy #1 is BRRR - solely be able to pay off investors. However, I can't find comps in the area to support an accurate ARV. There's zero comps in the area - no one is buying and selling duplexes in this rural market. I've reached out to local residential appraisers - no luck. None work with small multi-units.

What should be my next steps?