I did that lower mount thing for awile. It gets wet, gets dowsed with road kill juice, gets coated with tar, mildews and molds if uncared for, and collected dirt and road chips like nobody's biz. If you want to eat sandwich out of there, you're a better man than I. Keep it high. Keep it dry. I like that rear mounted concept. I've thought of putting one there myself but opted for a smaller sized roll bag instead and keep it on the rack.
