Spent many days in Capital Reef and camped many nights in Cathedral Valley, under the stars and even in one really nasty thunderstorm. The valley is great place to set up camp (just make sure you are in BLM lands). Great place is by Carl's Reservoir...
I believe that is a photo of the Moon Pyramid off Caineville Wash Road. Have you done the entire loop from Caineville Wash to Hartnet trail and back down to 24? If not, it is fantastic.
For those wanting to visit this park and this area; I highly suggest traveling these two trails if you have a vehicle that will make it.
On the Hartnet trail, after crossing the Fremont River, you get to run in the Bentonite Hills...
Further up, to the south desert overlook looks what I would imagine Mars looks like:
Then further up the trail you have the Cathedral Valley overlook; great for a sunset shot
But this trip will be in the lower part of the park. Setting up camp at Cedar Mesa, off the Notum Bullfrog road and doing some off-roading in the H3. A lot of trails there I have not seen; yet.
As for clear skies, well in Southern Utah during the summer, a clear sky is all you have to work with.
And yes, I know some great areas to take photos that are off the beaten trail. Some require a serious 4x4 to get to, some just a 2-wheel with some decent ground clearance. From great areas above Labyrinth Canyon looking down onto the Green River, to going down a decent trail (narrow swithback) to the Green river.
For more serious places...Top of the World, Dome Plateau, and some of the backroads in Arches are great too.