p2oh - this is lsutigger2 (don't tell anyone, but I'm at work)
Anyway, I think he signed up pretty early. Maybe during May. I really don't remember. I'll see if I can find any other info when I return home. A phone call to the pro shop at one of the courses may be good. The more rounds you work, the better the incentive. My DH got 2 free rounds of golf and a one day park pass last year and this year for working three days - one round each day. We're going in early February so he can use his free golf voouchers!
There are a variety of jobs and this past year they were still looking for volunteers pretty close to the date of the tourney.
Hope you can do this.
And as others have indicated, I don't think park attendance is greatly affected by the tournament.