Is it possible to put in an inflatable boat or kayak from any of the waterfront campsites? In other words...are the sites right up to the lake or would you have to wade through trees or grass etc

Yes, definitely

I was at site 51 last weekend and it would have been easy to do from there.

The island sites, yes!

Put it in from your campsite. Water is down about 5' so you will have mud.