I would say there are TWO spots at Kinder Crossing where you can camp in reasonable seclusion from the other site. The one site is quite large however (about the size of 2-3 plots of Tempe house property) of flat, open land adjacent to the creek and I believe that there are several secondary fire rings, but you will definitely be within view and even earshot of anybody else who may be camping there. This area will also tend to receive at least a couple dozen daytrippers on the weekend, so solitude is not likely.
As for fishing, there are several pools that are quite deep, but I've never fished there. The creek was nearly overrun with crawdads last time I was there. A friend and I grabbed about 30 and brought them back to camp for dinner. Didn't turn out as well as I had hoped.
But at least they're not in that creek anymore. (Invasive species... kill 'em all if you can!)
Oh, and the lower part of the road to the trailhead is absolutely not sedan friendly. So you may have an extra 1/4 mile hike than planned.