The biggest problem will be getting the needed clearance between the inside of the fender and the top of the tire, in other words, getting it far enough away from the tire. If you can't get quite enough clearance when pushing the official sizing limits of the Cascadia Hybrid, you may wish to order the Cascadia 29er V-Stay ($3 each on the PB site, you'll need two of them) which is 35mm longer to clear the taller tires.

For what it's worth I have Cascadia Road fenders and they just clear some 30mm CX tires, when the official limit is 28.