I realize I've probably missed your trip but thought I'd post anyhow. We've stayed at the Association Island KOA a few times including as recently as last weekend which was in fact their closing weekend for the year. We've made them our Thanksgiving weekend choice for the last couple of years. The premium sites are a little pricey at $75 during peak season but off season our premium site was $45. It's a beautiful location and a bit secluded which has pros & cons. Most notable con is it's approx. 30 minutes to decent shopping in Watertown. We usually shop on the way home since we pass by Watertown rather than give up camping time. We prefer the campsites on the West end of the island because of the spectacular sunsets but it can get windy as opposed to the East end.
2007 Shamrock F19 hybrid - 2010 (22 nights), 2011 (24 nights), 2012 (11 nights)
2013 Surveyor Select 235RKS - 2012 (6 nights), 2013 (32 nights), 2014 (26 nights), 2015 (37 nights), 2016 (14 nights)