2013 Kona Jake, 2008 Kona Major Jake, 2013 Kona Jake the Snake, 2006 Kona Kula, 2012 Ridley Excalibur, 2008 Surly Long Haul Trucker, 2001 LeMond Buenos Aires
Personally, I'd say that's too tight. You might be able to get it to "work" in the limited sense of being able to spin the tire without making contact with the frame, but any mud at all and it's going to start dragging. My CX frame, to give you a point of reference, has 55-60mm of space between the chain stays.
cantilever calipers are working off pivots, on the frame below the radius of the rim.
so frame cross braces and fork blades can allow better clearance
without the brakes being functionally, compromised.
you probably can do fine on dry courses , or really thin mud..
or have a friend with a hose ,
and a second bike for when sticky Mud starts to clog up the wheel turning ,
that's when the 2 bike hand off helps keep your speed up .. at the front.
Won't have to ride a mud laden bike , slowing you down.