Yea, you should actually ask your insurance company. I have Liberty Mutual and asked them all of these questions before using them for my trailer. They confirmed that I didn't even need Coachnet or such because my truck and trailer were both covered under the "Towing" plan I have. Added to the fact that the trailer is connected to the truck it is basically "double" covered. I also have roadside assistance with them as well.
My Travel trailer NADA at time of purchase was showing 42K for Liberty Mutual, and my policy which includes, fire, theft, damage, collision/comp is $20.00 per month.
I even went as far to ask, "If I am camping and a tree falls on it, is it covered" Yes.
If it is in my driveway and a tree falls on it? Yes.
If I have it stored somewhere and it is hit, broken into, vandalized or such? Yes.
Deductible, $10.00