Have you checked with a legal bod? If someone trespassed on private land and hurt themselves, as long as there was a sign up saying beware of the whatever, they could not be sued. If someone chooses to come on your land but you have a sign up at each end saying basically - you walk here but entirely at your own risk - are you covered? or is this different because it is a public footpath. thinking about it, you always see signs in public car parks saying you have parked at own risk? I would ask the question in those terms, of a legal and not an insurance body (so CAB?) before I went any further.