The BLM only has one developed site between State Bridge and Catamount, and that is Windy Point right below State Bridge. That has around 4 sites available. Anything else is dispersed camping, and those only a party or two at most. The Upper CO River Rec Guide shows you where people have traditionally dispersed camped in the past, and most of those sites have fire rings to help you know that you are in the correct place. As long as you are a private boater, you can camp anywhere you can find a space between State Bridge and Catamount.
Last year, the BLM posted Entering/Leaving Public Lands signs along the river corridor in that stretch. Look for these signs as you float down to help you locate if you are on private or public land.
Have a safe and fun trip!
-Bureau of Land Management
Colorado River Valley Field Office