Determining comps when there is nothing comparable??

[Kyle Gregg]

I am currently estimating what i could rent a 3/1 in my area of Baltimore. It is a side by side duplex on a small piece of land. The immediate surrounding area is somewhat rural but its not too far from more populated areas with large multi family buildings. 

My problem is that the comps are all condos/apartments in these large multi family buildings. Is it right estimate my rents based on these comps? There isn't many duplexes in this area to appropriately base monthly rent. 

Could this property be a potential problem, seeing that it is somewhat 'unique', when it comes time to find a tenant?