Sigh. Well... this is a new thing for ME to learn. I am on it, soon as the water gets warm enough for ME to get all wet!
Why wait?
Start with a kids sled on the driveway, parking lot, or other solid surface. Or you can use a training table which will get the dog used to being off the ground. That is the crucial step. Have the dog step in and then command it to sit, lay down, or whatever you want it to do. Make it remain for a few seconds at first then work up in time. When it is doing this well, move the sled into the yard or where there is a smooth surface of snow. Less than knee deep is preferred and I like a couple inches over the ankle as it gives some instability but not too much and it doesn't slip over the boot tops and get my feet wet and cold.
Have the dog hop into the sled. It will probably want to jump out as the sled will tilt due to the snow but rightened the sled and keep trying. You may have to grab the collar to help steady the dog but keep at it until he realizes he won't get hurt and doing so makes you happy. The first time he doesn't immediately try jumping out is a good time to stop for the first attempt. As he becomes comfortable jumping in and out of the sled, extend the relit ions and duration of being in the sled.
When this becomes easy for the dog, go back to the hard surface and add in moving the sled. This will require two people with the puller being able to start the sled moving without tugging.Go slow and work up from small successes. A buddy uses aRadio Flyer wagon but I haven't found one cheap enough yet.
After the dog is comfortable with a moving sled, go back and use your canoe on land. This should go quick as it isn't much different than what has already happened. I might even skip the sled for the canoe but they can be harder to move on snow as pulling them on a hard surface can damage them.
Before moving to open water you will need to get the dog under your control. That is basic obedience. Put him on a lead, put him on heel, and walk him toward the water. I'm betting the dog will break for a frozen lake but, if not, wait until there is some open water. When he breaks, draw him up short and make him. Hold his head up with the lead or by the collar and push his butt down with the other hand if necessary. When he is sitting, praise him, release him, put him at heel, and walk away. Repeat until he gets to the point he sits when commanded. This may take a while as he has had 5 years of being the boss. You will have to undo that and instill that you are the boss which is a lot harder with an adult dog.
When he sits reliably, walk closer to the water and repeat whenever he be begins to break. Don't let him in the water until he remains on heel and sits at the water's edge. When he does this correctly, take him off lead, release him from sit, and let him swim. I personally would work on the dog sitting on the edge off leash until released but it's your call.
At this point you can introduce the canoe in the water. Stay in the shallows where it is easier to control. Have the dog jump in and out of the canoe as well as sitting or laying down. Tow the dog and canoe in the shallows in the shallows until the dog is comfortable staying in the canoe. Then hop in and do short jaunts with the dog building up in time.
I did this with a 3+ year old Pointer and he became my best boating companion. It took about 2 months of 1x week day, twice weekend sessions to get to that point with most of the time being taken up with obedience and adjusting to moving/unstable situations. Getting sedan of a floating boat was a couple sessions.