Thanks, all, for the comments/suggestions.
But it sounds like everybody replying has a private (or primary) vehicle in addition to a SMB (or other RV). The thing I keep being told is: your SMB cannot be covered as an RV unless you have another car (to drive daily).
I have talked to Progressive and once I told them my SMB was my only vehicle, they said "No go." It's worth a lot more than the Actual Cash Value.
And it looks like "Agreed Value" policies are not issued for RVs. Classic cars appear to be the target there. Read about "Stated Value" policy language to get completely creeped out.