As mentioned the Black rock playa. I camped along the western edge where the vegetation starts. It was a few weeks after Burning Man and they had opened the area back up. If it's windy that will kick up a bunch of dust especially out in the middle.
Another area you might like is west of Denio Junction and south a few miles off 140. It's called Virgin Valley CG. There's a hot spring there with a proper pool built. The water seeps up ender the gravel on the bottom but there may be other campers there. They have a shower house using the spring water. Back towards Denio Junction is Bog Hot Spring. May be campers there too.