I figured I'd follow the Bizer link to see what is listed for people who are "day boaters"...the ones that haul their rigs to Winnipesaukee to spend a day and I was surprised.
Bizer lists a bunch of launch sites, but many do not have information regarding parking. That pretty much rules out those ramps for people coming to the lake with rigs that are not familiar with the area since no one will drive to a ramp with no information listed and risk that they can't park. The lake is a little too big to spend the day driving around looking for a place to launch.
That leaves only
8 launch sites identified by Bizer as having public parking, and one of those 8 has limited access because of a bridge.