Splitting the fender is what works for me. I can even run 28's on a race frame with fenders with a split setup. I also added a Sheldon Nut on the front to make things even easier.

You can buy the brackets here, or do what I did and bend em up with a vice and pliers out of rear rack brackets.

RCB Reacharound Fender Brackets : River City Bicycles



My setup, in action in the snow with 28c tires:

[IMG]Bianchi Slushy by tashipeacock1, on Flickr[/IMG]