My take would be find a campground in the south already open and plan to stay for a duration. Heading to a northern State campground not yet open would be high risk. Would not be good to arrive during opening week only to find they plan to stay closed. Campgrounds I called are not saying anything other than they are keeping a close eye on the situation. TBD probably by the State not campground.
Let us be honest, campgrounds are community social places that comprise of people from many different States. I imagine restrictions will be forth coming from the flu police for those campgrounds not yet open.