The train does run right next to the river for that entire stretch. It bothers some people but I've never had an issue (and in my experience, kids have loved it). You can car camp at Pumphouse, Radium, Rancho, and Statebridge. There are a number of campsites on the river but I can't remember how many are in the middle of the run. The best one I can remember is on an island on the left a little after Yarmony Rapid. Good flat spaces for tents and easy to spot from the river (there's one of those little metal brown forest service posts marking it, too). This would be towards the end of the run if you take out at Rancho, but closer to halfway if you go down to Statebridge. Make sure you stop at the hotsprings with the kids (about halfway between Eye of the Needle Rapid and Radium, on the left). And just downstream of the hotsprings and across the river are some good jumprocks if the kids are so inclined. Have fun!
"The world would be a better place if everyone kayaked."-Brad Ludden (Valhalla)
"You only get one chance to run a drop blind."-DD