the worst clashes occur at the front of the fork crown, because someone has been daft enough to specify AK fit brakes on a frameset with mudguard eyes. Simply because the head of a fastener on the back of the fork crown is smaller than the spacer on the back of a typical caliper assy, any clash is less of a problem.
You can convert a set of AK-fit DPs to nutted ones by either fitting so-called 'fender nuts' or by replacing the shorter centrebolt from a pair of brakes to the rear caliper, then using that caliper at the front. A spacer (a washer of the right size will work, eg a spacer from a V-brake brake block) at the back of the fork crown /brake bridge will allow nuts to be used in the conventional way to secure the brake/mudguard properly.
If you do this
a) the rear mudguard gets more clearance because the mudguard bridge doesn't have to be under the caliper and/or the brake bridge any more
b) the front mudguard is closer to the road and will actually do its job better.
If you do have to slot a mudguard fitting, consider folding the corners over a little, so that the fitting won't drop out as soon as the mounting is the slightest bit loose.
cheers