The Model T and other cars that have the springs exposed can be greased with this very elegant tool.
There are also a lot of variants on this tool that separates the leaves in a controlled fashion.
I just found this post by Tom Wesenberg where he mentions a problem I also noticed, which is that the rear springs are tucked way up inside the cross-member, making it difficult to access them for greasing. That's why I originally was hoping to remove the hanger nuts, to try to drop the spring down so I could get between the leaves.
The post includes a photo of his greasing tool, although I can't really see how it works.
https://www.fordbarn.com/forum/showp...90&postcount=2
That's going to be the real trick, getting the grease up in the midsection that's tucked into the cross-member.