[DGW]

Duffel bags work best. If they don't quite fit, you pull stuff out of the bag and throw it in the trunk where it will fit. On all my road trips shoes were always stuffed anywhere they fit. When you are traveling with a woman there are always more shoes than you can possibly imagine one person needing.
I've done road trips in a 70 911, 83 911, 87 911 and a 93 RS America. Packing was an art form in all cases. I always started with soft sided bags.
Highway 1 from SF south to around Hearst Castle is one of the greatest roads in the world. Be prepared for a lot of construction slow downs though. I did that drive a few months ago and there were quite a few sections of one lane road. If it fits your schedule, stop at Nepenthe, south of Carmel, for lunch, the view is fantastic.

Forgot to add, GP white RS America.