I checked Schneider's website for Square D breakers, and they don't offer an AFCI breaker larger than 20A. I dont know the manufacturer of your panel, but Square D is one of the major brands used in new construction these days, so if they don't offer AFCI breakers larger than 20A, then it's likely none of the other manufacturers do. Your best bet is to use metallic conduit for the feeder, or run it underground (if that is an option), and put out some rodent bait boxes.