Even filing the top of the front mount as much as I dare and pushing right up to bottom of headset I find clearance insufficient on my winter frame, mud tends to ball up around the part of the clip on the inside of the guard, i have had to stop to clear this even on days when the guards were clean at starting out. Previous guards had a shorter clip and was not a problem. The SKS ones seem to have a 'taller' clip. The clip is very strong and not feasible to bend it to shorten it.
I am going to check the 'up in fork underside' method, how does this work will Allen key brakes? - is it a case of fit around the exposed part of the brake bolt in front of the AK nut? Also how do I fix the guard as high up in the hole as possible and keep it from dropping down and sitting as low as it wants on the slotted hole/bolt?