In the end we found the springs and they were glorious. On the way back we were rewarded with a terrific SoCal sunset over some spikey mountains. These, and a few other nice views along the way I managed to capture in my soon-to-be-replaced camera gloria, and can be found here: https://picasaweb.google.com/105494084231616659850/CampingWithTAndS
Might be worth a trip back there some day. One of the nicer hot springs I've ever visited; a distinct lack of boreholes and concrete!