Since I have been mostly working along the idea that I will have the grid as our backup,
( as unreliable as it has been here in the middle of no where)
I have had plans to build a dc generator trailer for the back of our tractor, for those long outages we see here after large storms. I know that the PTO might be a tad slow for most pre made, but think I will still give it a try on an old airplane gen, just to see how much it can give.
Failing that some sort of matched axial might be in order.?.
If so I'll likely build with a single magnet rotor, and have some sort of ferrous material in, and backing the coils.
Mostly for heat dissipation, as this will be able to run full out as long as its needed. I think the dual axial stuff would be toast in no time. I also have no worries about drag and cogging driven on a PTO.