Yes, Flat Rock from Nashua is about 1.5 hours. I know other people have gone there and they have enjoyed it, but that was years, and several owners, ago. I have not heard much recently. I've driven by and you can see a water slide and mini golf from the road. I have not been in the campground, but it looks a little dated from the road. Not much to do in the immediate Lebanon/Rochester area, though Milton Lake is within 10 miles, and there is a great ice cream place (Lone Oak) within a mile or two.
By the way, I have an '02 Kiwi 23B.