Any way to change the default vertex colour?

So: vertex colours. In Unreal these default to white; in Blender, vertex colour data defaults to black. You can test this by creating a static mesh, selecting it, entering mesh paint mode, and then setting the ‘color view mode’ to RGB.

Is there any way to change the default from white to some other colour? I’ve got a shader I’d like to use across multiple objects; some of them have vertex colours created for them, and some do not.

The simple solution here is to invert the vertex colour when it’s being created and then re-invert it when shading in Unreal, but that’s not really ideal; I’d rather have vertex colours default to black for consistency.

Related: when you import an FBX, you can choose to import the vertex colours, ignore them (which is default for some bloody reason), or overwrite them completely- but you cannot import them if they are there and use a default if they are not.

Thanks in advance!