Ace of Diamonds CG is VERY small. I doubt anything much over 20 feet will fit. It is up a small, but steep, hill. There are very few amenities at all. We stay at the KOA frequently as my mother-in-law is in a nursing home in Herkimer. The campground is quite nice. It has a nice playground for kids, dog park, small swimming pool, etc. If you stay there, your receipt gives you a minimal discount on mining.
The campground at West Canada Creek looks nice -- we drive by it on our way to and from Herkimer. Check the mileage though -- it always feels like a long distance from the KOA to there.