There are horseboaters about. They even have a club!
http://www.horseboating.org.uk/
The biggest challenge to them is other canal users rather than BW.
Yes I know there is, in fact the prime mover and shaker of the org (which appears to be inactive nowadays) is, or was, someone I used to know vaguely some 25+ years ago, through a shared interest in draught animals.
BW is no more, it handed over its responsibilities in England and Wales to the CRT (Canal and Rivers Trust) more than 10 years ago.
I would say the biggest obstacle is neither the CRT nor other users, but rather the way in what might be called the restoration of the towpath's infrastructure or engineering has been done - with which I am sympathetic, and which I appreciate in the main, being an enthusiastic user of the Lancaster Canal's towpath on my bike. Sadly there were no thought or concessions made to preserving or maintaining a range of features which (we now know) were part of the functional history of the canals, and essential to the full understanding of how they were used commercially for most of their history. I don't for a moment think this was done - at least initially - for any reason other than lack of knowledge, lack of funds - and lack of foresight, too. Hardly surprising given the volunteer work parties 50 + years ago who were working to save the most vital and important parts of the canal network when the state body nominally charged with that responsibility were - or at least appeared to be - actively encouraging its decline into total dereliction. And few people fortold the massive upsurge in both leisure and heritage 'industries'.
One thing I have noticed is that, over the years, the antagonism and aggression, which used to be so commonly and generously on offer to all and any passer-by, from canal anglers sitting on the towpath surrounded by their mountains of paraphernalia, has almost entirely disappeared. IME at least.