Most important thing to know about Affleck Campground: You can't get in without a reservation. When you make a reservation, you receive the code via email for the combination lock at the campground entrance.
There are vault toilets and a trash dumpster here….that's it, but the sites are completely in the woods. You can't see this place from the road.
Site #14 was great. If you're interested in the California, Mormon Pioneer or Pony Express trails, there's a sign by site #44 indicating those National Historic Trails are right there. We didn't venture into the woods because the campground manager said there's a dead moose out there somewhere and the resident bear may be feeding on it. The resident bear in July 2018 is only about 250-300 pounds, and he had "brushed" against a tent the previous weekend.
The campground manager came by the site to review the rules, but he doesn't stay there. He told us this campground is busy on the weekend and deserted during the week. We were there on Friday and Saturday night, and about 6 out of 20 or so sites were occupied.
For bikers: There's a long, gradual hill outside the park that would be a good challenge for road bikers. There was an event while we were there. A trail through the park gets mountain bike traffic.