It's very possible and that's what most backpackers do. I'll give you some possible locations based on what I've done and heard other backpackers do.
December to Jan= Banana picking in Tully, Queensland. From what I've heard this can be a bit dangerous with all the slashing work involved. The machinery in storage sheds/ coolstores needs to be treated with caution as well, as some backpacker lost his fingers. This location is also home to the most venomous snake in the world, the Inland Taipan!
Early Jan, Feb, March= Pear/fruit picking in Shepparton, Victoria. This is what I did and I think it's pretty decent. Most farmers are of European background, Macedonians, Italians etc and are a good laugh, and they're not crazy rednecks like in other parts of Oz. My advice would be to camp out with the other workers/backpackers, as the only hostel in the town charges quite a bit for accommodation and setting you up with work. Always arrange work for yourself and never use a contractor. Just ask around at the farms. It'll probably be best to get here mid-January. The town is also quite decent for the bush, it's around 30,000 and even has quite a few decent girls. I actually had fun here. Get a membership at this gym called 24/7 fit. It's fairly cheap but the main reason for it is their showers. Well worth the $40 months. There's another gym called anytime fitness where you can get a free week trial. Great showers as well. The McDonalds in the centre has free wifi. Packed with backpackers usually.
March-May= Apple picking in Batlow, NSW. This is where most backpackers move onto. Organic farms as well, which you'll grow to love as they don't use any chemicals. Great cheap accommodation from what I've heard as well. Apple picking is much easier than pear picking and the temperatures should be rather cool/perfect by now.
That should get you done man. If I was you I'd just start in mid-January with the fruit picking. It'll be more than enough for your 88 days. There's quite a distance between Queensland and Victoria, although you could buy a camper van and drive down after you're done with the bananas.
There's also orange picking in Griffith NSW from Sep-April. Much harder than pear picking though, however, the town isn't far from Shepparton. Here's a list of what other fruits/vegetables you can pick, but I'd be careful with a lot of the jobs as they could be shocking jobs in terrible towns with appalling conditions.
http://nomadsworld.com/jobs/home/12-general/36-fruit-picking-seasons-in-australia