Just a little push...
FSR's and even phones work on the GMR run I outlined, that means you're able to scout ahead on this wonderful one lane road that goes between Baldy and GMR called Glendora Ridge Road and let folks know what's coming at you.
Plus!!!
And this is the big one...
I live in Whittier so if I don't have to drive a bunch just to go drive a bunch, I'll always choose that route.
But I digress...