Class A Insurance

There are some companies that will write the insurance when you do not use it full-time, and others that offer full-timers coverage. Make sure you purchase what you need. It is true, the older the motorhome, the less the premium will be for comprehensive and collision coverages. The liability coverage, any medical, etc should be the same no matter the year. It may however increase based on the weight of the motorhome. The bigger, the more damage it can cause. We have our full-timers policy with Progressive. Before we went full-time, we had State Farm who does not write full-timers policies.
The state/area where you are purchasing the insurance, your personal credit history, your driving record all play a role in the rate you receive. It is very hard to compare yours to someone else's because of the personal difference in the above.