I don't know where you get the idea from that you can only tow a shoe box unless you pass the test for a B&E licence. You may now drive a car/caravan combination weighing up to 3500kg so long as the caravan doesn't weigh more than the kerbweight of the car. Assuming an average car sort of car with a kerbweight of about 1200kg and fully loaded about 1650kg, you could legally tow a decent sized caravan of up to 1200kg and still meet both criteria. If you stick to the recommended 85% of the car's kerbweight as your limit rather than the legal maximum, the caravan would weigh 1020kg and you'd have an even bigger margin.