I am getting a dog pack for my 43pound Border Collie. She is classic BC very thin, lithe and active. I'm not looking for something that can carry a lot of stuff but I think once she has the pack on she will realize she "has a job" and will concentrate on the hike. I'm seriously thinking of the Ruff Wear Approach Pack. To me the fit is most important. Does anyone have exprience with this pack on this body type of dog? Any positive input would be appreciated.