Based on my experience with this lens (we've owned one since August, and although it sleeps in my wife's bag, it often hitches a ride in my bag if she isn't shooting, while my 16-35 waits for someone to appreciate it), you'd probably need a 6"x6" filter rig to cover the deep corners of this lens, and therefore I think your hopes are simply to be dashed. Stick with a 16-35 and the reality of 82mm filters. Someone provided some links to 95mm CPLs for the Zeiss 15, and they were $450 and $700 each.