I'd rather try the same trick in Portland than LA, though we may not be able to satisfy the high desert requirement. Still require some driving, but it wouldn't be as brutal.
I think you could do it in 5-6hr of driving starting in Portland (drive to coast, drive to Mt Hood, and then drive east somewhere, maybe Shaniko). Without traffic (hah) its probably about 2hr less driving in LA (LA->Santa Monica->Big Bear(if there is snow)->Lucerne Valley)