DIY Parking: How to mark lines/spaces in a field?

Any advice you all may have on how to plan out and line an outdoor wedding's parking in a field is very appreciated! My mom thinks "parking attendant" volunteers are needed, but I'd feel bad making someone stand out there and prevent a cluster****. I don't really trust people to create a good situation on their own, however. There are places off a long, long gravel driveway where if you try to get into the field too soon or in the wrong place you're going to be in trouble and in too much of a drop off. Should I try to buy flags and stakes? Get a chalk line roller thingy? How do I prevent guest parking mayhem? via /r/weddingplanning http://ift.tt/2u27dGj