In SoCal, the most cold water wear I ever used was a farmer john wetsuit, booties, polypro shirt and light jacket. The water rarely gets below 50°, a drysuit is total overkill.
Now I fish in a much colder place where it rains all the time. When the water temperature is in the low 40's, same as the air temp and it's raining, a drysuit would be good, but most of the time I wear waterproof pants with shorts underneath(polypro long johns if it's cold), polypro shirt, sweatshirt and waterproof shell. Since I know how to get back on my kayak if I get dumped, I don't plan on swimming around for an hour or two figuring out what to do. The hardest thing to keep warm are my hands. Not many gloves that keep your hands warm and are flexible enough for fishing. If you are fishing in any type of marginal conditions, better be wearing that PFD.
We stop fishing when the rod guides ice up, so we do a fair bit of
dressing for the conditions.