Two options, I was in a way doing the same as you but decided differently.
One(ideal to retain cluster)buy a lightning wiring harness and move the relays, fuse box and all other stuff under the seat behind the battery. All you need to extend is the tail light wires which would be simple.
Two(what I did), modify your stock harness by extending the ignition and hand control wires then fit the relay and what not under the seat.
*problem*, I didn't extend the gauge cluster wires since there are so many, so I had no cluster. Also it is pretty in depth removing the harness. Otherwise you are left with a bunch of stuff up front like you have now. So after I rewired my harness I ended up not liking how it looked so I rewired it back to stock and settled for cutting down the stock fairing.
Hope this helps.
Brandon