Upgraded the milk crate to the EMGO top case. The verdict is still out though. I like that it is light, waterproof and cheap. I was originally looking at larger pelican type case for up there but I didn't like the weight of the cases. The sizes I was looking at started at around 10lbs... a lot of extra weight to have sitting there before I put anything in it.
I opted for not using the base plate that came with it for weight savings and ensuring that the box wouldn't pop off mid whoops. For those familiar KLR's you will understand my fear of adding extra weight to the sub-frame. Not really an issue if you check the bolts every once in a while but still. Less weight hanging off the frame outside of the original dimensions of the bike the better.
I made a large one piece washer or plate with some steel I hade laying around. Traced out a cradboard template of the holes on the OEM rack and planned to have the bolts come through tight to the corners. I even snuck the front corners under the OEM racks welded support brackets. I treated the plate to some primer and truck bed liner to give it a bit of rust proofing and extra grip.
I sandwiched the box, OEM rack and plate together with some SS M6 bolts, washers, nuts and one of the brackets that came with the box. Yes I know the bracket should be flipped, but I didn't want the rails of the bracket to create high pressure points on the plastic of the box. This will be covered with a scap piece of carpet tile (doubles as a side stand plate when in need).
Ride safe!!
Matt