Speaking of breaking axles: I have a 1930s/40s (?) Maxi steel hub (this came before Maxicar) with an extended threaded portion, and the bearing is all the way on the outside. Basically, imagine a standard freewheel rear hub, but the threaded portion is not 1/2" or so, but goes on for a bit over 1", and there is almost no axle overhang. The last few threads are machined off, don't know why... (Maybe freewheels, see below, weren't threaded all the way?)
It's a smart idea, but you need a special freewheel that isn't stepped down on the inside, but has a constant, large inner diameter. Obviously, such a freewheel wouldn't allow small cogs, but back then, 16 and 17 were common small cogs, and that should work fine.
BTW, other Maxi hubs I have seen don't have this feature. And then, just after 1945, came the Maxi-Car hubs with oversized axles, and the problem was moot in France... That may be the reason why the cassette hubs that were developed around then by Tank and others (?) didn't go anywhere. If your axles don't break, there is little to improve on the basic design of a freewheel hub.
Jan Heine, Seattle
P. S.: Anybody got a freewheel that fits the above description? In French threading? For Sale?
P.P.S.: One wonders why we've had to deal with broken Campy axles for over 40 years when the solution is so obvious - make the axle bigger!