If you could supply the mules like electric trains are supplied, you might just as well replace the powerful mules with lightweight power pickup runners that the boats connect to with a cord. Boats would only need a few minutes of battery power for situations that aren't as easy as running straight along the canal.
The difficulty I think is that there aren't many board purpose-built for canals: they are purpose-built for canals and rivers and many navigable rivers are to canals like oceans to the rivers, much wider and unpredictable environment. That also makes that "pickup runner" idea I posted much harder than I first thought, and pulling mules (modern as well as actual). Historical pictures of badge towing show astonishingly long lines, I believe that this is because rivers tend to have wide shallow waters between the part that is deep enough for navigation and the part that is dry enough for a tow-path.
The good news is that multimodal boats should work just fine, might even be easy to make the electrified parts support enough autopilot to allow the time to be used below deck for engine maintenance and the like. Barge operation is mostly waiting anyways and getting rid of the last instances of unscheduled interactivity might be really easy (if it hasn't been achieved yet? Primary obstacle is that the market just isn't very big)
