That's probably why the PO didn't do it. Seems like you could cut the tube portion of the mount that's welded to the grab bar, making it short enough that the early style OEM lights which are smaller, or the sportbike lights like on the front would work.
If you don't want to hack on the grab bar light mounts, you'll need to get some longer TS stems which are available, but you'll have to search.
Also a little tacky, but you could make it look good... Bolt a strap or flat plate right onto the mount of the grabbar. Then you could put any light you want on it. Hanging down a little bit or straight back.