On the way into Bryce, there is BLM camping at
Dixie National Forest Dispersed Camping Area
https://maps.app.goo.gl/yjjc5tGtDqEcBbM78
We drove the loop around the Campground. Big rig friendly.
We stayed at Wahweep on lake Powel. You can also dry camp at Lone Rock at lake Powel. Although I've seen pictures of the lake dried up at Lone Rock. You can walk out to it now.
When we left the area we went through an RV self wash in Page to get all the dust off before we left the area. We had been out west for a while through several dust storms.
If touring Zion, route 9 goes through a narrow tunnel and switch backs. No RVs. We were in a dually. They stopped traffic at the other end of the tunnel so we could go through. We stayed at Hurricane while touring Zion.