I must be doing something right since in 39 years of dirt riding I have never had an issue with fork seals. Nada, never. Problem is I don't what I am doing right. When I sold my 92 KX500 it still had the original fork seals after 14 years of abusing it - no leaks (actually the KX never leaked a drop of anything ever - pretty darn good, my kids KTM leaks from everywhere). Reading Dons post mad me realize that the one thing that I always do is align the forks before I tighten the front axle. I never put a support between the tire and fender when trailering; I never have cleaned under the seals with film (although that sounds like a great idea); never used forkskins, etc. Anyway....food for thought. It is possible that alignment is one of the keys. As for ATF, I used it for years as fork fluid. My dad used to tell me that type A was 8wt and Type F was 15wt. Not sure if that totally true but it is an easy rhyme to remember. In the old days I used the A in most of my bikes. Presently I use F in the low-end non-cartridge type forks, F in my CBR900RR street bike and A in the high-end non-cartridge forks. In my fancy dual-chamber cartridge forks I am using 5wt fork oil in the inner-chamber and synthetic ATF "A" in the outer chamber for reduced stiction. Works for me. It is also a decent cost saving for those who may have 5 or 6 bikes at home. Cam.
PS the KTM forks leak like hell but they did when we got the bike. Time for a fix this winter.