Your panniers will stick out further than your handlebars. I mount my tent perpendicular to my rack deck. The ends do not overhang past the panniers but it make it a pain to get into my panniers without unloading all the bulky items from the deck. Arkel makes a bag that holds the tent vertical but I never figured out why. I considured replaceing my 24" pole sections with 18" sections from Quest Outfitters but it won't make an improvement in how I pack.