I've rented a few similar lakefront places in Maine and NY State, though not for a whole month. One through Craigslist, one through VRBO, and I can't remember how I found the third. My advice is to ask a lot of Qs (don't take anything for granted), research the area well, and get a lot of pix from the owner. One of the places we rented was on a lake full of motorboats -- not the secluded, peaceful getaway we expected. One had a lower-level room with a door that opened directly into a hillside and was teeming with bugs! OMG, I never got over that one. Also that owner was constantly coming and going which is also not what we expected or wanted. The last one had no internet or phone reception, which isn't that rare in rural mountainous areas, but it caused some inconvenience. Also the electricity was very limited -- there were serious power outages and we were annoyed that the owner wouldn't give us a partial refund for that inconvenience. I'm not sure if I could have come up with screening questions that would have allowed me to rule out the bug room place, but I think I might have addressed most of the other issues. It's hard though, because the demand for vacation rentals is such that owners don't need to provide much info.
Overall I had a better experience renting "hotel rooms" at places whose rooms were actually private cabins. It wasn't as private but the gap between expectations and reality was less and the accountability was better. There was a lovely place like that on Schroon Lake in the NY Adirondacks but I can't remember the name (it's probably changed management since I was there anyway). Good luck!
