I am also needing to change my duplex ( main and guest house) to a SFR. Did you do it and was it difficult? I actually can not refinance my home right now because the other duplexes in the area are not very nice and my SFR is uncomaparable.. therefore, without comps the bank can not approve my refi.
If you did this successfully, I'd appreciate your advice and perhaps if you could share the route you took to save me a little leg work? ( literally, I have a broken foot! )