The only group rides I know of are the poker runs that happen from time to time. I've seen some video of the Johnson Valley PR and we like to start in finish the riding season by donig the Barstow runs in October & April.
Hit me up when you're ready to head out. I live near the coast, but I go to the desert every few weeks to ride. I rode in Yucca Valley & Johnson Valley last weekend, and I love riding up in the high desert.