there are no publicly available tools for completely or partially automating the migration. Am I missing something here?Nope, I dont' think such a public tool exists.
I've failed to locate a comprehensible migration guide or documentation about the best practices of the migration.I don't think such a document exists either.
Visage is not an option for us, as the future of the project is unclear at this point.IMO, not using Visage at this stage (and perhaps ever) is a good idea.
for your advice or pointers to relevant documentation.Just start the manual conversion process - as a side benefit, you will learn the JavaFX 2 platform.