Temps have been in the 70s up there - a couple of weekends ago when a cold front went through it dropped to 29 and there was some frost - but generally it has been nice (be prepared).
The most modern campsite (and busiest) is by the Rob Roy boat ramp. There was lots of logging activity last fall around there to get rid of some of the beetle kill.
If you want to get away from people, just follow some of the FS roads and find a spot. There is some private land near the lake, so get a map and make sure you are on forest service land before you set up camp.
There are a ton of moose around there right now - the elk are a little tougher to find, but they are around too.