Though step taxiing does offer a good high power engine checking opportunity, It offers dangers (loss of control) as well. Many operators will not permit step taxiing, because of numerous accidents in that phase of "flight". If you are step taxiing, it's best to have most of your attention outside. The engine checks by feel and ear are okay, but if you have to look for the engine controls, and indications, you might be too distracted from the task of safely step taxiing.
As for canoes, yup, it can be test flying. Toward safer external loads, Transport Canada is now requiring a design approval for external loads on fixed wing aircraft. There are tricks to making canoe flying safer. It's the other stuff which is carried externally which has Transport Canada's attention. Years ago, a set of antlers as an external load prevented a safe flight in a PA18. The resulting fatal accident, was a catalyst for more regulation.
Pilot DAR