Just wrap a big hide chew up several times in any old paper, the dog will know what's inside... stand back and watch as the dog eagerly rips the paper to shreds to get to the treat... worked every year since the 1960s!
I can't think of much that would be more demeaning for a dog than to put clothes on it.
I know this is anthropomorphising but when my dog had an injured foot some time ago, he wouldn't go out of the house with a bandage on on the injury. As soon as I removed the bandage, he seemed perfectly happy to go out. I'm sure he'd be the same with a jacket, Barbour or otherwise.
A dog chew is a good idea or a large bone. Avoid chocolate, even that supposedly for dogs unless you want to be cleaning the carpet.