Is NY decided upon? There's also Lake Anna, VA, and Deep Creek, MD. Both have camping, bars, boats, and I'm sure Air BnB. I know for fact one can rent houses at Deep Creek that will easily accommodate 15-20 people, or multiple houses side by side. I also know you can rent party boats at Deep Creek, cruise around, then park at docks around the lake and walk right up to the restaurants and bars.
We just went to the fair for carnival food and it was disappointing. Watching the 4x4 races at the dirt track, however, was not.