A friend gave me a pair of saddlebags for my XB-600. TourMaster, soft shell types. Because of the wide body plastics it fits just like a regular motorcycle. It has two support straps that go over the top and one of the straps goes across the seat bucket. But it's not a problem. In fact, with the saddlebag storage I can use the seat bucket for an additional battery. If I like the saddlebags I might upgrade to a hard shell type.
I did some searching on this forum and the internet and only came up with a few people who have tried this (a guy had them on his XB-700i. I wonder why? Wouldn't saddlebags be a good alternative to the bubble trunk that people always complain about? Plus, my motorcycle friend said bags are better for balance because a truck puts weight in the rear where it doesn't help as much. However, with bags I am concerned about security. Often saddlebags are just buckled with straps, velcro and zippers. I may have to look into how to lock / prevent easy access. I know nothing is fool-proof, but at least some prevention is better than simply pulling a zipper.
Anyway, I'll post pics as I modify and set it up, and test it out. It's raining cats and dogs right now, so I haven't actually put the bike with bags on the road. That will be the real test.