Can't give any advice without a bit more information. What is the MTPLM of the caravan? What is the weight of the Focus? What is the max towing weight of the Focus? If you don't know the weights of the vehicles could you look them up on the net or in the brochures? This would give us something to go on. The suitability of the Focus range varies enormously, some of the eco models have low tow weights whilst some of the larger diesels have quite useful limits.