You most certainly can get the airbox out without removing the rear fenders. Keep the quad inside where it's warm so the airbox is a little more flexible. Remove the lid and filter, remove the two bolts holding it in and disconnect the hoses on the front. Slide it back as far as you can. Then stand directly behind the quad, put your hand down over the front edge of the airbox, between the locating pegs and pull back. It's tight, but it will pop out. Once it's out, trim the tapered part off the locating pegs and you'll be able to easily yank the box without a fight.