Some of you following my bamboo thread will see that I will be needing to rent a trencher and trench out a trench roughly 40' - 45' long, 30" deep. I've not used a trencher before but I'll be using a Vermeer for this. The rental is $100 for 4 hours and the rental store is only 1 mile from the job site, on the same road. How fast do these things go? Will I be able to have it done in under 4 hours? What should I charge to do the job and will I have to know anything special before using it?