Fix dealer registration

Applies a new round of fixes to finalize dealer registration for AC.
Yeah, this was to avoid having to do a schema change.

The tax ID won't have to *do* anything, so I'll elect to leave it as-is rather than refactor the variable name just to have to refactor it back later.

So if it turns out the client needs me to do a bunch of stuff with the tax ID, you can laugh at me then. :)