From what I can tell, the version of the game that backers have is just the standalone, regardless of what they backed.
Hate to be a disappointment here, but
unless you emailed Larian to request a standalone (Steam-free) DVD version, what will be shipped is a Steam-dependent version, requiring a Steam account (see Larian's KS comments
here and
here about the need for a day one patch and their decision to use Steam to deliver it).