I know that some people are reading this thread and thinking that Brad is being overcautious. As a result of the meetings I go to I have contact with the leaders of other user groups. I also have 41 years experience in servicing fire alarm systems. I learned a lot about liability.
A person connected with the disc golf association that put in the course at Shelby Farms told me they had to disband because of a dispute over a liability issue on the disc golf course.
I also learned that Memphis Whitewater Canoe Club disbanded because of liability issues. They closed all of their web site except for the forum and no longer support memberships.
I also know of several subrogation attempts by insurance companies. Not made up hypothetical possibilities, but real life situations where a person's health insurance was looking to recover what they spent on minor emergency care of their policy holder.
In reality, any insurance company that spends money on someone because of an injury will try to find a way to recover that expenditure from someone else.
This is the way the world works now.