I don't ever call ahead. But I am a full timer and have no real planned destination like a weekend camper. That said.
I don't call ahead, I just show up with my 4 small dogs and as of yet have never been turned away where their was a limit number of dogs CG rule.
It's just good company policy for them to say no on the phone based on the posted CG rules. If I was an owner I would too. I found if you just pull in they often make exceptions to the dog rule cause you are already there, they see you and what you have, and they want your money!
Most have a weight limit more often than a limit on number of dogs.
I did stop at one CG which I was hoping to stay a month and they had a 3 dog limit, weight limit 35lbs. I just said if I added up the total weight of all 4 or my dogs I would be under the 35 lb rule! The owner laughed and said yes I guess you would be waved me in. :C