Yeah, I wish there were rattlesnake avoidance trainers on the east coast, I could never find any.
There are other ways to train your dog to avoid snakes if a professional isn't available however. One encounter with an aggressive large non venomous, or only mildly venomous snake will teach your (my) insanely stubbornly curious dog quick.
Any herpetologist type friends with bull snakes can learn your pup fast, assuming they're not too timid about letting their snake bite a dog. With anything in life, the trick is making sure they learn the hard way, so it sticks. If they don't lose decidedly, they'll just enjoy the concept of snake encounters.
Still I agree, if you love your pup, sometimes, the best thing to do is leave them at home, as much as it hurts to see them cry.