I think that mapping the site in detail, while useful to a small number of punters who can read a map (and then actually do so) does little more than demonstrate that we've tried.
Marking / taping areas similarly: even where we have taped stuff off I often go round at the end of the event and pick up torn tape off the deck.
Fundamental issue, which FF has already called out is that are a set of punters who are responsible (who can be let loose unsupervised) and a bunch who aren't (for whom only a free-range no rules site or highly marked and marshalled track is suitable). The huge challenge is working out which group each punter falls into: you can't tell from their truck or tires and its a brave club official who simply tells certain people they're not welcome at an event based on subjective criteria / gut feel...
Members of this forum, by virtue of being folk who can read, write and take advice are going to almost all fall into the former category!