Have you thought about ASKING the landowners that have given you permission to hunt on their property whether your dog is welcome as well? Seems like that might make sense - even in California. How would any of us, even those of us landowners, be able to speak for someone else we've never met?
For what it's worth to me as a landowner, if you ask, and I grant permission for you to hunt on my land, but then you insist that you "refuse to hunt without a dog present", and I, for some reason, don't WANT your dog present, then I'll retract my offer. You lose. Why should I feel bad if you REFUSE A FAVOR I WAS OFFERING YOU? I've heard stories about cutting off your own nose to spite your face before, just never thought it was something I wanted to try.
A few reasons that I might refuse access to a hunter that insists on bringing a dog.
1) Wrong dog for the job: My property isn't a dog park, if I offer you permission to hunt rabbits, a lab doesn't make sense. Beagles, sure, but walking around shooting a shotgun with a lab at your side doesn't make it rabbit hunting. Wanna exercise with your dog, again, go to a dog park.
2) Cattle, horses, or other livestock on the property. I don't care whether you say it's well trained, if we both find out that it has ONE DAY where it decides not to listen and it pulls down a colt, calf, lamb, kid, etc, I'm still out that livestock. Or maybe the dog gets separated from you and you call it back, inadvertently running it through a herd of skittish cows, in turn, running them through the fence (been there more than once). Many livestock will be calm with a hunter walking nearby, but dogs can be a different story.
3) Other dogs on the property. I have a few guys that hunt on property that's right behind a neighbors property and the neighbor has farm dogs that aren't penned up. Usually the dogs stay out of the way of lone hunters, but I had an instance where I gave permission to a couple guys for birds, not knowing they were bringing dogs, and the farm dogs came out to run off the "intruders", and tore up the guys bird dogs. Since the neighbors dogs DO have permission to be on my land, and I wouldn't have let the guys bring their hunting dogs KNOWING such an incident could happen, I had to side with my neighbor - their hunting dogs weren't in the right place.
I'm sure there are plenty of other reasons why other landowners might not allow it, but again, the simplest answer is to ASK THEM.