Maybe you could book a late afternoon flight, or evening when ever your dog is most relaxed.. try to do something that will get him tired out before you leave.. a long walk if its not to cold out, a long trip walking around petsmart, play ball in the house, just something that would really really exhaust him.
Practice now getting him used to the crate.. or use the same bag you plan on traveling with in your car for short rides leading up to a longer one..keep him in the bag , reward him for being a good boy etc.. you have a month to do this..
Rescue remedy is NOT a sediative, its used for situations just like this...
If your not comfortable flying with him barking, perhaps you could hire someeone else to fly down there with him, I am going to Florida Jan 7th and tickets were only 114.00 each way.. Im sure that is cheaper then the transport service.
....I honestly wouldnt care if the transport company was bonded, I would still try anyway possible to keep him with you!!
Here is the link to Rescue Remedy
Natural stress relief for pets - Rescue® Remedy Pet