Road insurance for non-Americans in the US

We're not Americans but have traveled the US extensively on holidays (43 states and counting!) If we were to buy an RV, possibly a truck + 5th wheeler, let's say we store them for 10 months and come over for a 2 months long vacation once a year. What kind of insurance would we need? Does Good Sam provide road insurance for RV's (and the truck on its own too)? Do we need different plans for storage vs. use?

We're not looking for a quote, obviously, but a range would help in thinking and seeing if this is even feasible for us. $2K a year? $5K? $10K?

Thanks in advance!