Fitting a new harness is pretty easy, just carefully mark the old connections and take lots of photos before removing the old harness. On my RS I did have to remove the fairing to be able to properly get to the connections for the indicators and horn.
Also I recently had a couple of wires burn in my loom and rather than replace the loom I replaced the wires, cutting out the burned sections and soldering in new wire. It was a little fiddly but not a hard job either so you might not have to replace the whole loom.
