Shopkeeper - multiple inventory problems

I have come across a problem, and I don’t like the answer.

In Shopkeeper every product is a document/resource. I am working on a clothing site and have items with multiple sizes (small, medium, large) which are handled with extra options. So far so good.

But the inventory tracking is for each product or sku. In reality you need to track each attribute as a seperate sku, so that you know when you run out of small red shirts or large green shirts. So to get the inventor to track properly you need to set up 9 documents (assuming you had 3 sizes and 3 colors)!

I think that would be a problem with most shopping carts. I like the flexibility of using ditto to display the products but I don’t see how practical it is to have each product a resource.

Wouldn’t it be possible to do it like in the demo:
http://shopkeeper.wdevblog.net.ru/english_demo/example_2.html

Have Radio-Buttons or something to let the users deside with colors they wanna have?

Read the documentation to finde out how thats done.

Well that’s what I have now. The problem is tracking the inventory. The inventory is matched to the product id, so need to have an id for each size to track individual inventories. I really depends on how you want to run you shop. In this case the client wants to display sold out on individual sizes and doesn’t not want to manually change the status of each product.