When I do mine the plan was to cut and weld.
On the Land Rover Salisbury axles I have the axle is splined both ends and there is an internally splined drive member that bolts to the hub at the outer end.
My plan was to cut the outer end of the axle and bevel it. Then grind out the splines in the drive member and bevel the outer rim.
The axle will be pressed back into the drive member so that it is the right length and squared up. The beveled end of the axle can then be welded making the outer end of the drive member into a big plug weld. The inside edge will also be welded around where the axle fits into the inside of the drive member.
I doubt that my electric tractor will produce enough power or torque to bother a welded axle (fingers crossed, after breaking two transaxles!).
However, I am now thinking of allowing myself a little more width and just using the shorter standard axle shaft on both sides. It will just mean, for the sake of 6" extra width, my tractor won't fit in through my house doors anymore.
I believe with your American axles there are plenty of places that have axles off the shelf or will respline. So much better and easier.