I probably state the obvious here but that does not stop me. First I would look at any permit requirements your town has regarding pits, schedules, weight limits, which days of use and hours. If convenient, mirror those, if not, try to negotiate what you think is best. It would seem to me that you have an excellent opportunity to work with them to have a very convenient source of material for your road without having to pay for transport like the rest of us do. I would try to negotiate (or legislate-would need a lawyer here) to find a way to agree on what to do during the time most towns "post" their roads due to mud season. You have your work cut out for you but it will require diplomatic skills on both sides and if that fails, good lawyers on both sides.
Keep in mind the term "fair and equitable". It would seem to me that if any property owner, commercial or not, puts much more burden/use/wear and tear on the road then that requires more compensation. It would need to stay "reasonable" though, in order to be defensible in Small Claims Court. Once you form a statutory road association the dues and such are set by the property owners at a legally called meeting.
Best of luck.