-- Last Updated: May-29-13 12:20 AM EST --
They or the marina staff might be able to help you. I wrote a description of paddling at Lake Chelan as a day trip (it's on Pnet.'s Places To Paddle section). My impression from the stretch that we paddled is that there aren't a lot of bail-out or camping areas, but they do have some designated boat-in campsites. The park had an info board with a brief description of each one. Maybe their website has a map with the same info.
One way to get an idea of the shoreline terrain is simply to read topo maps of the area you're interested in. This won't tell you all you need to know, but it's a start.