Big-time thanks for the feedback on the 29er fenders. I'll steer clear of those. Sounds like they'd definitely be too big, if not at least kinda funny looking, on my hybrid, and while I'm not necessarily averse to trying to modify things a little, things that work w/o mods are always easier. Seems like there should be a 50mm fender, but as tarwheel said, they don't always make the perfect size.

So... based on what I've heard so far I think I'll stick with the 45mm fenders. My 40mm rear tire is actually looking a little tired and old (a few threads visible on one of the sidewalls) at last tube change. If I keep the 45mm fenders and they don't work with the 40mm tire, I guess I'll just go ahead and get a 35 mm tire for the rear, and I've already got a 35mm tire in front, so front shouldn't be a problem. A basic 700x35mm city-type tire (which I probably need soon anyway) is all I'd need in that scenario.

Thanks guys!