Allowed? I thought I read somewhere that it was mandatory!
Seriously though, if you mean is it legal to have alcohol on your campsite and outside of the trailer, most laws consider your campsite to be similar to a motel room (a private place of residence, legally speaking), where alcohol is permitted within the boundaries of the campsite. Some jurisdictions and privately owned campgrounds may have different rules, and alcohol may be banned on specific dates to curb rowdyism. Best bet is to call ahead, or check websites of potential destinations.
2011 Grand Caravan