A shorter cable outer will give you a straighter and more efficient cable line. There are plenty of devices on the market, I can't remember where I found that picture or what Google terms I used but you will just need to spend a few minutes trying different terms and trying the more specialised bike-builders' suppliers. However a frame-mounted collar would send the cable to the brake from the side of the frame whereas a traditional seatpost clamp mounted stopper such as you've got will at least be central, making brake setup much easier. Here's what you should be aiming to achieve:
It looks as if Surly make a longer device that will deal with your very elevated seatpost clamp more neatly: