Would it be possible for you to add support for VFS in your coming Recalbox update? The package that needs to be included is kodi-vfs-rar for this to work.
Sorry, I'm not a developer and I don't know if this is possible.
I recommend that you check the next version's changelog if any such changes are already scheduled (if you have one, just wait for the next version to be released - there is no scheduled date):
You can check in the issues if there is already an issue open with this request, if there is, comment it, if not, you can open an issue requesting this inclusion: