How about Hays Haven's ramp? It's 45 minutes up the river in Chester. Pretty secure, protected location. I kept my slow boat there for 8 years without problems. $20.00 to park and use the ramp. I am not sure what the time limit is , but I am pretty sure it covers a weekend. The ramp is short but steep. A heavy boat probably needs FWD on the tow vechicle. There are a couple of Cig 38's that are stored on trailers and put in with 3/4 ton PU's. Fresh water doesn't hurt either. The only problem is that the "No Wake" zone in Essex and the two in Saybrook seem like they take forever to get through. FYI those "no Wake" zones are heavily patrolled on weekends in the summer.
Another possibility is to use the public ramp and ask "Between the Bridges if you can park in their visitors lot. It's not as secure as Hays but it's closer to the Sound.