How much is the average travel trailer insurance rate?

I am interested in getting a modern (2005 +) travel trailer approx 25-28′. I wanted to know what the average rate would be to insure it. Also, is it a requirement to get it insured?
Thanks.
Please give a actual ESTIMATED rate. If I wanted an actual price, I would contact my insurace agent, but I just need an estimated rate. (California)