If you aren't too conceerned about staying stock, you can ignore the OEM latch and install a bolt to hold the bag onto the antler. Look at the antler and you'll see there's a big triangle in the bottom of the front leg, which lines up with the metal doubler just behind the latch. I drilled mine through there and installed some 3/16 full-thread bolts, with nuts to hold them to the antler, and a matching hole in the bag, and the bag slips over the bolt end, which is drilled to accept a small cowling pin or cotter pin. This makes sure the bag can't come off, and adds a little bit of anti-theft,.as the pin is not accessible once tha bag is closed. And, no, it has never leaked water in. I can take some pics if anyone wants to see it.
Unfortunately it also just about guarantees massive damage if you ever "hook" a bag on something solid, since the bolt won't shear off as easily as the OEM latch, I think.