Great report. One observation and one question.
Observation: The place you camped at Double Hot Springs was the same place our little ExPo group camped in May of 2009. Of course, it was much hotter then! That was on Memorial day at the same stock tank that was too cold when you got to it. As soon as we got there we diverted the hot water away from the stock tank so it could cool! By 5pm it was down to 104 degrees so we stripped down and jumped in! Same thing next morning - a nice soak, followed by a "field shower" (took a bucket of hot water from the tank and dumped it on me, then soaped up, grabbed another bucket to rinse and after rinsing, jumped back in.) Fantastic! It's the only time I've ever been on a 6 day camping trip and felt "clean" every morning!
Question: Looks like you took the old Applegate Trail from Sulphur to Black Rock Point? I thought that area was closed to vehicles as part of the Wilderness Study Area?
EDIT: Disregard my last. Looks like that area is open to travel, it's the area further to the North and East (the "Eastern Arm" of the Black Rock Desert) that is designated Wilderness.