Good point about the conduit.
To the GP, Transformers work a lot better when you have a tap changer set properly.
Transformers cause starting problems due to the cubic wind loading, not because the iron losses are high, but because volts/hz is highest at startup and there is no power available. Depending how you look at it, iron losses are actually almost zero at startup and will climb with hz to the 1.6 power ( silicon steel) or as high as 1.9 or so with newer amorphous iron.
The solution is to just use at least 2 sets of primary coils. If your alternator is very efficient then you may be able to get away with a WYE/Delta switch on the primary.
Or just get a bigger transformer and accept 4 times the losses overall. (50% efficient alternator, full load at .6T, startup at 1.2T)
I suspect that most of these axial flux alternators are mostly sine wave machines, in which case there would also be a 5-10% benefit to wiring up a 12 pulse rectifier.