I have to concur. State of Massachusetts does not require insurance on trailers sub 10,000 lbs. You do have to register it however.
Word to the wise for you. I don't know what the use for your trailer will be. But if you are going to be on the highway for any time I suggest the largest tires you can find. This will save your hubs.. Speaking of trailer hubs..... Don't forget to grease them yearly.
Glenn