That's why I like rafting trips, I can bring everything but the kitchen sink. And my husband handles the oars!
Do you have any stores nearby that sell packs so you can work a little on getting fitted correctly? I know weight is definitely going to be an issue. There is probably an REI store in your area. They have a very nice selection of packs, but they don't allow dogs in their stores.
Like any sport, it will take a bit for your dog to get used to something on their back and the additional weight. But if you go a lot, it shouldn't be too hard. It sounds great to have your dog help out more. I wish I could train my dogs to pull our raft off the rocks when we get stuck!
~ Stacey with Hunter, Lucy and Riot, missing Reilly, Tiger and Pennie