The elevation at Mammoth will be a good test for how you do at altitude. Death Ride goes a wee bit higher, though. Get some friends and go camp at Grover Hot Springs in June and ride the passes. That will be great prep. There's usually a group of Luna Chix folks there around the same weekend we do our altitude camp (first weekend in June, I think it is the 6th or so) - at least there have been the last couple of years. And if you go the weekend we do, even though you're not riding "with" us, you'd be assured of SAG support - we're pretty generous with our SAG because we think it's good publicity for TNT.

If you want some possible training rides in Sonoma, Marin and Napa which will get you ready feel free to let me know!