Well if uae4arm can use a zip file or lha file as a harddisk then there would be no need to reprocess everything into hdf files, you could just use the packs as hard drives dierctly. It would require a modified boot floppy disc image though, which would scan the packs for whdload slaves and readmes on the fly and put them in a little menu.
Can someone have a look and see if archives are supprted as hard drives in uae4arm? It has to be zip and lha file support to be useful. If so I can probably make a new boot floppy for it.