That looks great. I did not consider simply moving the box back, I understood someone to say that you could switch the resevoir to the back of the box, but it then hung down 2 inches under the frame where the rear hugger could hit it during full compression. It looks like your battery box may be subject to interfere with the hugger, but maybe it is not possible if you are using the stock dog bones so the rear suspension does not use all of the area under the seat.
BTW, I dig the paint scheme, looks great.