It might seem odd for someone who has recently built a Bantam Tugboat, but I've never felt that canal boats are good subjects for large, radio control models. They are at home in narrow waterways but look wrong to me when on a lake.
This might be the exception to the rule however, the Waterbus that plies its trade in central Birmingham,
A really short prototype, not much longer than the Bantam. It is a little boat on the canal so wouldn't have that "fish out of water" feel when on a lake.
I'd suggest that any model needs to be at least 1/12th scale to fit the mechanical bits. Going even bigger might be nice, perhaps Action Man size?
If you want to sail, details here.