I bought the Wolfman E-12 Saddlebags to use on day trips with my Green DRZ. These are smaller saddlebags for enduro bikes, and they fit the KLX perfectly. They are quality bags, made of heavy duty material and zippers, and liked them right away. Just what I needed for overnighters on the KLX 400.
Yet, they have migrated over to the KLR and stayed there for several months. I don't plan on removing them anytime soon. These are great bags and I am amazed at how much they can hold. They will carry several plastic shopping bags of stuff, but are small and low profile enough to stay out of the way when not needed. Between errands and weekend rides, they have found a home on the KLR.
The above picture comes from Wolfman's installation sheet and shows why the E-12 bags don't require mounting racks. They lay across the seat with two adjustable 2 inch straps and the lower mounting straps fasten wherever needed. The "Tension-O-Matic Rear Mounting" strap was a pain and I removed it from the bags. Even without this rear harness the bags stay secure and ride just fine.
The bags are not waterproof, so I simply sprayed waterproofing on them. After several short trips through "normal" rain showers, nothing in them has ever been wet. Try riding long distance through heavy downpours or crossing a deep river, and your results may vary. A dry bag would be very useful in this situation. I did not buy them for that sort of riding so that's never been a problem for me. While I bought them for the smaller bike, they work great and look good on the KLR and I would buy them again. These bags are a quality solution for extra carrying capacity.