jajwrigh ... your equipment/utility trailer should be insured under your truck/vehicle policy which does not include the items on the trailer ... your equipment should be covered under your company liability insurance ... at least that is how mine is set up .
It is covered under the tow vehicle's policy. You can buy extra coverage which we have for our landscape/car trailer. It was $20 for 6 months or 12 months I can't remember. It was worth it to us when you have a 4,000 pound $20,000 thousand dollar investment in tow.
Your business liability will not cover what is on the trailer. To cover the contents off the trailer it needs to be added as what is called inland marine. If a mower flies off the trailer and damages someones car or property your auto insurance will pay for that. Liability only covers the other persons property.