Not sure. I have a private Blue Cross policy (single) I'm 50, and claimed "truck driver" as occupation. This was pointed out as a "high risk" occupation and thus I pay a higher risk rate. Also, they've gone up about 4-5% year the last 2 years. If you shop for a policy through a major provider, if there's any way you can make yourself out to be "unemployed" it may lower your rate. Once the application process is over, they don't care what occupation you may end up in. I could now be a secretary but they never ask for for my current occupation to keep their records updated for renewal purposes and I've tried asking how to change my occupation to "retired" because I am, they never responded back. So it's all about the application process. If you're thinking of becoming an O/O and are currently "between jobs", do not claim any current occupation. If you are currently a driver, then do what you feel you need to do as far as the application. Many will claim "insurance application fraud" or some such, but trust me, they won't look out for your interests in the future, regardless what sort of changes you may actually deal with.
I've never read the fine print of the application, but if there is no clause stating you must inform the insurance carrier of any change in occupation, I wouldn't worry about future claims (as a driver) being denied and/or policy revocation.