I just walked out to the garage to re-check your sugestion.
You are right!, after removing the handlebar mounts, you have no problem loosening the nut on top of the steering head.
Now you have two loose nuts on the ped. The other problem you have is that there is no way to get a crescent wrench on the lower steering head nut, even if you stand it on end.
I suppose you might take the top nut to the tool store and try to find something to fit, as it is the same size as the bottom nut which requires a thin wall socket.
By the way, heating and hammering metal is not a millwright's job.