+1 on the JC WHitney Case. I got the 42L for the top case on my KLR. It has survived drops, slams, ineptitude, break-in attempts and looks a little rough, but mostly where I scratched the paint off that orange strip. I have had it come off the back rack when I hit a huge pothole on the freeway going 50 kph (not paying attention to road), flip off the back of the bike and skid into the curb. Net damage: slight crack by one hinge (closed with bonding agent) and some scratches.
It ain't pretty, but it works, and it even has a crappy little plastic bump for a back rest already attached. You get more than you pay for with this trunk.