Not sure how Stobart, Brawn F1 are working it, but most F1 teams have thier own trucks, but the drivers they use are mainly agency drivers, from specialist agencies who supply truck drivers for F1 teams. They normally get the truck to the circuit, clean it, park it and fly home. They then get flown back to get the trucks home or to the next circuit. When it’s quiet on the racing circuit they go and work elsewhere.
I suppose the Stobart drivers are going to work it a bit like this, but will be employed by the same company all the time.