I have the DMY trunk and made my own rack from 1/4" plate. I took the short OEM backrest and cut off the mount tabs and welded them to the rack then had it chromed. Slides right back in to the rest mounts. The stuff that comes with the trunk is not very stout so I replaced all that with some homebrewed parts also. BTW
watch the hinges on that trunk. The pins may give you trouble.