Mine was a simple and cheap solution-if you are happy bleeding your parts.
Take the rear brake hose off and run a length of black heat shrink over that is wide enough to put the Reverb hose through too.
Put the Reverb hose through, re-attach bleed the Reverb and brake and it looks pretty clean as you now have a single line from front to rear.
To finish it put one cable tie around the seatclamp to hold the Reverb hose tight and turn the seat 360 degrees. The hose then coils around the post and when the seat extends up and down the slack cable doesn't catch the tyre/suspension.