Howdy Jamie!
You will have a TON of hootin' hollerin' fun at Mickey's Backyard BBQ, complete with singing, dancing and awesome character interaction! I would suggest leaving Disney's Art of Animation Resort at 5:00 for a 6:30 showtime. The easiest and most scenic route would be to travel to Magic Kingdom by bus, followed by a direct boat from the Magic Kingdom boat launches to Disney's Fort Wilderness Resort. You'll be dropped off very close to the pavilion holding Mickey's Backyard BBQ and if in doubt, simply ask a Cast Member. The pavilion is only about 100 yards away from the boat dock!
You chose a "practically perfect" date to visit Mickey's Backyard BBQ, as Magic Kingdom's proposed closing time for all guests is 1:00 a.m. After your hoedown, perhaps you can celebrate into the wee hours. I suggest checking the
calendar as your trip approaches to verify the operating hours, and also remember park admission will be required if visiting Magic Kingdom.
Hope this helps, Jamie, and have a MAGICAL vacation!
Sherri