45s are NOT cut with greater modulation (if they were the sound would be louder through the speakers), the goal of the mastering guys is same volume, so the idea that different anti-skate is required is far fetched. Same anti-skate.
I have quite a few 45s that are obviously cut at higher levels. IOW, they play louder. Also, when we cut at 45 on our lathe (I run an LP mastering operation, FWIW) we find that we can cut certain frequencies at higher levels easier than 33. I think where you are having a problem is the assumption that the 'mastering guys' are going for the 'same volume'. We might and we might not. Usually we cut with two goals:
1) see if we can get it all on the side and
2) don't over cut such that the stylus gets knocked out of the groove or the cut goes over the previous adjacent groove.
Its pretty well impossible to overload the cutter system- the main limit is cutting a groove that a cartridge can track without distortion. A lot depends on the signal that is being recorded and they are not all the same else the planet would be a boring place :)
So if friction due to modulation is indeed a factor in skating forces, it would be a mistake to assume that it will be a constant- IOW it is indeed a variable.