jag90,
the most widely available discount seems to be AAA for the campsites. Disney is usually rolling out room-only discounts (not counting free dining offers) and usually only the cabins at the Fort qualify for those.
Like NoM, I just got back from the Fort (she and I were actually in the same loop
). I too got a 15% discount.
I had made my reservation last year and called to ask if a AAA discount was available for my visit about 6 weeks before arrival. I have nearly always gotten an AAA discount for all my visits but this was one of the few where the Disney CM asked for my AAA membership number to put on the ressie. So you might need to really be a member.
AAA discounts vary by time of year. Busy/full times don't have discounts but summer is a slower time at the Fort when you are coming so it might work out for you. There are only <so many> discounts available so if you hear of a member here getting a discount for the same type of site on your dates, that doesn't mean you automatically will get one. When they get all claimed, they're gone. Also sometimes discounts are only available for certain site types (Premium only but not Preferreds for example).
Our advice is keep trying. When you make your ressie you might ask and not get one but as people with discounts cancel one might open up so people do add it after a ressie has been made. The level of discount varies between 5-20% so every little bit helps.
You don't have to book this through AAA to get the discount. Discounts like this are NOT available through the on-line ressie system but you can make the ressie for the dates you want on-line at rack rates then call and inquire about discount availabilty.
Good luck this summer!
Bama Ed
PS - I hope you find the camping lifestyle very relaxing. You'll be spoiled by the Fort - it's the best campground I've stayed in (but not the most expensive)!