I was staying at The Lodge in Castle Rock State Park for a long weekend. This park is just north of City Of Rocks National Reserve which is a world class rock climbing destination. Though I am not a rock climber there are also a whole bunch of nice SOTA summits in the area. I picked CI-131 as I could see it from the front porch of The Lodge. In fact when I was on top, my wife, looking through binoculars, could see me waving at her. How often can your wife actually see you on a summit if she is not also with you?
There are no trails up to the summit. So, you just need to park and head off. You definitely want to come in from the south side as it is a much more do-able hike. I am not sure I would say easy -- it is around 700' in about a half mile. The junipers are not so thick that you lose sight of the summit for long on the way up. You do not want to get any further west than my tracks as shown below as the hillside gets even rockier than it already is. (Another route would be to park at the cemetery on the southeast side and come up that way. There is a bit more elevation gain that way and the junipers seem to be a bit thicker.)
Expect to pick your way through rubble the whole way up and down. I think it took me 35 +/- minutes to get to the top. On the way I crossed a couple barbed wire fences. One was low enough to step over the other had a section high enough I easily bent under it. There were no "No Trespassing" signs that I saw. There is also a geocache on top so my guess is folks go up this hill reasonably often.
When on the summit there are great views of the Castle Rock Park and the surrounding valley. There are plenty of junipers to attach your pole to, or you could throw wires over the tops of some. You can actually see the AT&T cell tower a couple miles to the south so no problems with voice and data coverage. When sitting down though be careful of the cactus. I managed to put my hand down on top of an old one and came up with a palm full of needles.
From mid-June through mid-August this area gets pretty hot. If you want to do this summit during that time of year go early in the day.
Scott/K7ZO