Hi Deborah,
Mondeo TD and Caravan:
You need a 4/5 berth because you need room for a family of four? or you just fancy some extra space for the two of you? More berths mean more weight.
If you can't cut down on the number of berths - then looking at an older van is a good way of reducing weight. In the past, UK vans were equipped with less stuff than today.
New UK vans have had loads of "conveniences" added to them - probably just to give the sales person something to talk about and differentiate their "product" from a similar looking caravan from somebody else - rather than be used by the owner on a daily basis.
You will need to ask yourself some serious questions about what facilities are really necessary in the caravan, especially if you plan to be staying at sites with good facilities. Do you need an oven? do you really need a heated shower bathroom? do you need carpets?
We tow a German 3-berth caravan of 800 kg (minimum weight) - typically 950 kg with all our stuff inside. So it can be done.
Beyond this there are legal requirements to towing, and there are also recommendations:
Legal - The following are legal limits that you cannot exceed.
Nose-weight is how much load the caravan "dumps" on the back of your car - and the legal maximum is the LOWEST value that your car, tow-bar or caravan can accept or apply.
Gross train weight is the total weight of your car, caravan, you and your family, clothing, and any other stuff you put in the car or caravan. You must never exceed the posted GTW (usually documented on a label on the drivers' door post).
Maximum towing weight is a limit imposed by the car manufacturer - if your caravan is near the legal towing weight - you can move weight into the car. But in any case you must not exceed the GTW, and if you are a novice you don't want to try towing close to either the GTW or caravan limits.
Recommendations:
Organisations like the caravan club have been helpful to newbies by suggesting towing limit recommendations - the 85% guideline is a good example.
If your caravan weighs less than the 85% guideline, then you shouldn't experience any unhappy towing problems on your first trip.
Robert