but have offered voluntarily to pay them, and there is no option to pay for a live-on licence

the Canal & Rivers Trust have decided that there is a disticntion between live-on and moored boats that only get lived on for touring.

That's what it said in "Towpath", the august respected broadsheet. With respect to K&A in Bath. Free at any chandlers or canal visitor centre.

On the Gloucester & Sharpness there are local by-laws that cleary state that you cannot stay more than 2 weeks in the parish. Seasonal workers/volunteers do move parishes to comply with that. It is clearly not academic. Nimby or no.
And all boats on canals are liable to the terms and conditions. By putting a boat on a canl you are subject to them. Now what is the legal distinction that says they can't levy what charges they deem appropriate?

In my young days they had signs on the towpath that clearly stated that riding bikes was against their rules. It did not necessarilly stop cyclist of all ages but it obviously dated from days when horse drawn butties were common. They were not unknown when I was young, and in the 70's Caggy Jones was still using Joe to tow.