We always do a canoe trip on the May Long weekend. It's the end of May so things aren't usually quite as severe as they can be earlier in the spring. 

We don't have any special cold weather clothing; we are just extra cautious. We always have a full set of clothes including warm layers in a dry bag. I always have a toque and gloves and have rain coat and rain pants. 

I wear my hiking boots with wool socks. We are quite practiced at getting in and out of the boat without getting feet wet. It means you're not as quick at entries and exits but there is almost always a way to do it without getting your feet wet if you're committed to it. We don't mess with any routes that would require us to wade or line the canoe at this time of year. 

We always wear our PFDs this time of year and each of our PFDs has a "ditch kit" in the pocket. It has a lighter, an emergency foil blanket, water purifying tabs, water container (which is an unlubricated condom, weird but it works!), basic first aid (butterfly bandages, crazy glue, bandages and wipes). It fits in a really small bag that fits nicely in our PFD pockets. You may lose your pack but you won't lose your PFD cuz you're wearing it!

We don't travel enough in cold water conditions to justify the expense of a dry suit or wet suit. We are just Very Cautious and take no risks. I realize this isn't the perfect solution but we are comfortable with our skills and gear as is.