I believe that we have two different threads on insurance being
discussed.  General liability insurance is what an event organizer
might require of a participant, while inland marine insurance would
cover loss of or damage to one's property while "in transit."

  "Definitions of Inland Marine coverage can be found in the NILS
(formerly the National Insurance Law Service) glossary:

    "Coverage for property that involves an element of transportation.
    The property must be actually in transit, held by a bailee, at a
    fixed location that is an instrument of transportation, or be a
    movable type of goods that is often at different locations.

    "Transportation of goods over land. The term now includes any goods
    in transit anywhere except on the high seas.

    "Bridges and tunnels are also considered proper subjects for inland
    marine insurance, because they are instruments of transportation."

  "But as a practical matter, the most important thing to remember
about inland marine insurance is that it covers property in transit
or mobile property, whereas standard property insurance normally
covers items located within 100 feet of a specific physical address."

Some homeowner's insurance policies do offer a limited amount of
coverage for personal goods stored away from the specified physical
address.  One should check their policy.  Based on participation in
[entertainment] events, an important thing to consider is how one's
insurance company defines "commercial."  It is best to check with
one's insurance agent.

Joe Orens