The important thing is to be sure the company has a good understanding of RVs. If not, it might be better to pay a bit more because RVs have unique problems - e.g., they're both a house and a vehicle. The same company seldom covers everything adequately, meaning your stick house, your RV, your cars, and all your other toys and necessities.
By the way, you would want at least minimal coverage on the RV even when it's in storage. What if a disaster happens and damage isn't covered while it's stored? I'm thinking of flooding, wildfires, power lines that come down onto it if outside, an electrical fire inside a storage building, a propane tank exploding, etc.
ArdraF