S. egleis, S. coronis, and S. zerene all look like good options. Sadly I didn't get any shots of the underwing.
Here are a couple of caterpillars on a Ruta graveolens in my backyard. The second specimen (picture #2) doesn't look very healthy.
Picture #4 and #5 taken on July 7, 2013. The caterpillar has attached itself to one of the stems of the plant.
Hyalophora gloveri (Sonoran group), Female
Santa Rita Mountains, Box Canyon, Santa Cruz County, Arizona, USA
July 31, 1999
Collected at lights
~11:00 pm
5,000 ft. a.s.l.
Coll. Bill Reynolds
Several individuals were congregated under a rock