Rincon Peak is a great hike. It is both rough and steep in a lot of places, with 1-3 ft steps common along the trail. We did it with 5 Boy Scouts, ages 12-13, and 3 leaders. It took 5-1/2 hours to get from the Miller Creek trailhead to the Happy Valley Camp. We cached some water along the way so we wouldn’t have to carry it all the way up. After reaching camp we dropped packs and headed for the summit - a 4 hour trip up and back. At the end it's steep. Really steep. The views from Rincon Peak are awesome in every direction.
Campground is very nice, smooth pine-needle areas surrounded by tall Ponderosas and Junipers. There are 3 sites, with fire pits, plenty of tent areas, a bear box, and a (gross) latrine. Plenty of deadfall firewood around. There was a little bit of stagnant water in the creek next to the camp - with a good filter probably drinkable. The night we stayed a storm came in and the wind at the top of the trees was very strong, but down at ground level not bad at all. It was probably 20deg warmer in the camp than up at the summit a couple hours earlier.
Next morning a much faster 3 hour descent back to the trailhead. Feet are a little sore but you really feel like you've done something when you finish this one.
Note- there is a lot of disagreement on mileage from various sources. The posted signs show 4.9 to the camp from trailhead, then 3.2 to the summit from there. A GPS we had along showed less distance, but the signal was not always strong and it ‘skipped’ parts of the trail. Plan for this to be a 16 mile round trip, not 13 like it says in the Falcon Guide attached in this website. YMMV.