I think your dropout can take the hitch that you have now (I may be wrong about that). I am guessing the issue is the struts for your rack and fender are somehow interfering with the hitch.

Another option is to use alternative mounts for the fender and rack. It will probably be simpler to order the Burley hitch though. If the new hitch does not work you could explore mounting your rack and fender on the seat stays.