Does Hunter have ball drive or like to tug? If so, go in the bathroom and tug or tease him up with the ball and have him jump in and out of the tub(no water) get him use to the tub first.
I have a hand held shower attachment which helps.
After he's desensitized to the tub turn on the water when he's in there and let him get use to the sound. Play with the ball in the water, but don't bathe him. Eventually he should see that there is nothing harmful or scary in the tub or the water.
My male was fearful of the tub at first, but got over it instantly when a ball appeared. He loves baths, I think having the shower attachment helps, the dogs love the massage feature.