I camped in Tunnel Mtn 1 for six nights at the beginning of August. It's much more developed than I'm used to. Generally it was clean, well maintained and comfortable. The view of mountains was great, and in loop C, the sites weren't overly close together. There were mosquitos, but that's just nature.
Most of the other campers for the first five nights seemed to be family groups. They were quiet and took pretty good care to keep their sites clean. Final night there was a group of noisy kids--to my amazement, despite the alcohol after 11 pm ban, it appeared that a taxi delivered them a supply of booze at 11. As noted elsewhere, there wasn't any onsite supervision. I think they were thrown out the next morning, but I was on the road that day.
Still, for the most part, the campground is very pleasant. I was tent camping, and thought the sites were quite fine for tenting.