Black rock canyon isn't rock crawling but its fun. I have some fun 4x4 trails on gps north off eureka. I also have a fun 40 mile loop on gps that passes eureka its desert and washes and canyons.
It's worth checking out Silver City and Mammoth while you're out there. There appears to be some mostly-intact structures on private property above Mammoth that would be cool to check out too, but I don't know who to talk to or if they allow access. It's heavily signed, so I doubt it.