Hi Fred ~ I often paddle with a friend who brings along her large Golden Retriever. She puts Max in the front seat of her Wildeness Systems large open cockpit tandem, and he behaves admirably. She has not had issues with steering, but she does sit in the back. The freeboard at times is lacking in bumpy/windy conditions, but they tend to stay closer to shore. He never paddles; preferring to snooze with his head on the forward deck.
I have heard that a pack of well trained Chihuahuas make for nice moveable ballast.
Kyle