(This might belong in the Commerce forum, was unsure where to put it.) I'm fairly new to episerver, so sorry if I'm asking stupid questions.

We are moving our ProductImages out of Epi, and handeling them in a external service, that will provide epi with only a (string)path and a (string)type. I'm making a scheduled job to iterate over our products, and for each product iterate over our variants to find all the images for that variant and store them on the variant.

But I'm unsure about how to best store this data on the variant. Each variant needs to store a property for the main packshot, a property for the main modelshot, and a collection of the remaining images. 

One could say that i should store them in the folderstructure as extentions of the ImageData or MediaData classes. But we do not need nor wan't to have this in the allready bloated folderstructure, as it would never be managed in the editor, everything would be managed programaticly. So I'm hoping that the answer is not that this is how you should do this. 

The solution i have been trying to implement, storing the data in a class that extends the block class:

public class ProductImageBlock : BlockData
{
    public virtual string Type { get; set; }
    public virtual string Path { get; set; }
}

These are added to the BaseVariant class like this: 

public class BaseVariant : VariationContent
{
   ...
   public virtual ProductImageBlock PackshotMain { get; set; }
   public virtual ProductImageBlock ModelshotMain { get; set; }
   public virtual IList<ProductImageBlock> Images { get; set; }
}

And in the scheduled job i do the following: 

var wcVariant = variant.CreateWritableClone<BaseVariant>();
var changed = false;

if (mainPackshot != null && mainPackshot != wcVariant.PackshotMain)
{
    changed = true;
    wcVariant.PackshotMain = mainPackshot;
}

if (mainModelshot != null && mainModelshot != wcVariant.ModelshotMain)
{
    changed = true;
    wcVariant.ModelshotMain = mainModelshot;
}

if (images != null && images.Count > 0 && images.Equals(wcVariant.Images))
{
    changed = true;
    wcVariant.Images = images;
}

if (!changed)
    continue;

var contentRefrence = _contentRepository.Save(wcVariant, SaveAction.Publish | SaveAction.SkipValidation, AccessLevel.NoAccess);

Inspecting wcVariant in debug, i can see the blocks with data on it. But if i load the variant from the contentRefrence after the save, there is a block on variant, but the fields of the block are both null.

Am i doing something oviously wrong in my attempt above, or can it be fixed with a slight adjustment?
Or is there a better aproch to this, that i should implement instead?

Thanks in advance for any answers.