Hello rob,
If the charger is too hot to touch, and you have never seen of heard the fan operate, my suspicion is that there is a fault.
It is not uncommon for chargers to become warm when opperating, but they should never become so hot that you cannot touch them. at that sort of temperature (About70C) many pastics and some others materials will start to loose structural strength.
It is not realistically possible for anyone on this forum to accuratley diagnose or suggest the correct remidial repairs, so get it checked out by your caravan dealer or qualified electrician.
iperating
ten it is indanger of affecting any plastics in its vicinity