Odetah in Bozrah, we stayed there a few years back and enjoyed it. Not the closest to Mystic but a good base to tour the whole area from. Reviews lately seem to run hot and cold on it though.
X2 Was there near the end of July if I remember correctly it was about $65 a night with FHU. I have a drop on my hitch for my tow, be carefull when you pull into the cg. If you get my idea.
Yeah, geography of the campground is very hilly, can be tough on the larger rigs and anything with a low clearance to the ground. Putting that aside thought the place is well run/maintained.
2007 Toyota Tacoma, Double Cab 4x4 Max Towing 6,500lbs GCWR 11,100lbs
2011 Jayco X20E, Pro Series 800lb Weight Distributing Hitch
Husky Sway Control Bar, Prodigy Electronic Brake Control
If you can get by without hookups, both casinos have RV overnight parking free. They are both just a short drive from Mystic. There are also Pilot stations not far that you can dump your tanks at. CT campgrounds are expensive.