UPDATE!! if your at the gate with your passenger window to the gate stay right on Shangri La Boulevard then bear right onto Sunset Boulevard, pass the first street on the right (Shamrock Circle) stay on Sunset Boulevard it takes a hard right as soon as you make the right there is a short dirt road on the right that leads to a rather large make shift beach you can launch from, its is NOT PRIVATE PROPERTY and full size Bass Boats can launch from there with ease, My buddy and I put his 19 foot Cajun in there with absolutely no trouble what so ever, there was 3 other trucks and trailers down there, you DO NEED 4 wheel drive because it is all packed sand, but none the less an easy launch
Heres the link to the intersection of Sunset Boulevard and Peaceful Lane its a google maps link when it comes up switch to Satellite View and zoom in the beach is in the 6 O'clock position on the bend in Sunset Boulevard
http://maps.google.com/maps?q=Sunset+Boulevard+and+Peaceful+Lane+Wareham+Mass&hl=en&sll=41.792721,-70.642068&sspn=0.002712,0.006856&z=15
Hope this helps