Is to add this to the build command: -dp T4VSHost!Microsoft.Data.Entity.Design.VisualStudio.Directives.FallbackT4VSHostProcessor!"C:\Program Files (x86)\Microsoft Visual Studio 14.0\Common7\IDE\Microsoft.Data.Entity.Design.dll"
I do this manually at the moment but love the way you went about 'fixing' the transform on build and think the rest of the community could benefit from this.
As a maintainer of NuGet package https://www.nuget.org/packages/Clarius.TransformOnBuild-unofficial/ I received the following letter from one user