I've got Wandefu panniers on my KLR in California, and you are right -- it's hard to keep things tidy with the panniers opening to the side. It's not completely unmanageable, especially if you add some keeper strings to keep the lids from opening beyond 90 degrees. Another excellent strategy is to employ bags inside the panniers that match the interior dimensions. Just open the pannier and remove the bag...

cheers!