My problem is the following: We want to upload supplementary material for bookchapters I'm editing. We have decided to use figshare.com for this. One advantage is that they supply all material with a DOI. But (as far as I understand) they do only so when material is made available for the public, not for private data.
Now, it would be a little strange to make supplementary material available a long time before publication (possibly more than a year).
How may I obtain a permanent reference (doi, link, etc) to the supplementary material which I can add to the respective bookchapter already without making said supplements visible to the public?
And if this is not possible, what would be a workaround? Make it public just shortly before handing in the edited volume to our publisher (this would still be months before the publication date)? Just refer to the account (not a single file) on figshare the material will be hosted on? Include a placeholder DOI within the chapter and include it after we received page proofs from the publisher? Just publish the supplementary material already because nobody cares?