It looks like the Arkel rack attaches to the seat post. I think that's ok. Maybe it depends on what your seat post is made out of. 10 miles is a long way to carry a laptop on your back. When I first started commuting, I actually developed some upper body strength in my arms & back from the backpack! Then I got a rack and became a proper cyclist, all leg muscle and spaghetti arms. I wouldn't have minded keeping the upper body strength, but I hated the sweat on my back.
2009 Trek 7.2FX WSD, brooks Champion Flyer S, commuter bike