I know a lot of the kids from this area and going to head up to Noosa and the surrounds, just to avoid the hype from the GC, you may be worth calling the tourism office and getting their thoughts?
Noosa don't hold planned activities but there are alot of schoolies headed that way. Alot go for the camping at Lake cooroobah and the houseboats up there. My aunt runs a hotel up at Noosa and they are booked full for schoolies.
I live in Noosa, there are usually some schoolies here. But there are no planned activities in Noosa. They catch buses down to Moloolaba. It's not at all wild like the Gold Coast.
With a little inspiration, imagination and forward planning, a day involving screaming hordes of children descending on your home in search of fairy bread can be fun.