Be also aware that you MUSt have dependable equipment. What happens when you breakdown and the bees start to overheat? Will you replace them? I spoke with a gentleman that had another way to skin the cat. He rented a tractor from a large rental agency, and when there was trouble INSISTED that they bring a replacement tractor immediately.
Ian - I bet you know how to work on your trucks yourself. Otherwise it can be expensive. pulled two broken axles(the part with the bolt circle you see where a "hub cap" would go on a cop car) out of a Mack today. It took about 1- 1/2 hours to diagnose, remove, and prep for new parts. Having trucks towed to the dealer can get expensive.
Crazy greasy Roland