Unfortunately, we're only able to offer a hardcover version of our main reward - Cults of the Blood Gods - for this campaign.
With the exception of Chicago By Night, the other V5 books are from a different company (published by White Wolf and distributed by Modiphius) and they won't be in the same warehouse once Cults of the Blood Gods is printed so the logistics would be a little complicated.
We're able to do the PDF add-ons because all of the PDFs are available via DriveThruRPG/Storytellers Vault and sending those out is pretty manageable using their tools.
Since Cults of the Blood Gods is still quite some time from publication, it would likely be easier to purchase the existing hardcover V5 books from a local retailer or trusted online store. Chicago By Night is currently en route to distribution and will likely be released into the book and hobby trade shortly after this campaign ends.