I am considering building a moveable tractor, however our property is not level; it has gentle slopes. The tractor designs I've seen so far are proposing either pvc or lumber rails, which when moved to the sloped areas would provide a "gap" betweent the grade and the rail. Can anyone suggest something pliable which could be used as the bottom rail - even if I have to have a lumber rail above? I'm PICTURING something like a garden hose but a bit more substantial that would follow the contors of the land when moved to a "curvy" area. With all the creative energy out here.... HELP!!