caravan heaters

Hi.

when we go winter caravaning we have a problem keeping the far end off the van warm,in our case it is the bathroom. The problem is that our present van is eight metres long and is fitted with truma warm air blower,which if I remember correct is the same system that we had years ago in a van half the size,

the only way round this for us is to put a convecter heater in the bathroom.     any thoughts on this