be very carefull when buying 3.5 ton recovery vehicles,check the unladen weights as they are all around the 2.2 to 2.3 ton. which will only give you a pay load of 1.2 ton. most vehicles are about 1.5ton in weight, also take into consideration the unladen weight also includes a full tank of fuel and the driver. as vosa will now prosecute if you are found overweight.
best advice get yourself an operators licence as you will definately know that you are legal.