George, we are just trying to maintain the difference between a campsite and an Aire hence short overnight stopovers not setting up camp.
Obviously if its a private Aire the site owner will decide.
We also push for no advance booking but in the UK thats very difficult so we ask sites to allow non booking or same day booking if they need to let people onto site.
We are not against more small basic campsites and some enquiries go that way but by recommending 48 hours it keeps things as simple as possible for those who tour and need these short stay overnight stops.