Hi Erica,
I work for a footwear retailer and we have a similar problem when working out how to categorize the extra items and its always something we have a bit of discussion about.
I think the first check would be a quick logic one, does it feel like the products can be easily grouped? For example I can see there are a few pairs of gloves/warmers that seems like a logic way people would want to shop.
The next step we normally look at is search data, even if you aren't planning on doing seo if there is sufficient search volume around, for example, a exoffico belt - chances are people will want to view them as a category.
You've got quite a nice product display for a single item so I wouldn't say that the individual items need an extra category. However, what we've done on our site is, when we know we only have the item for a short season the category page is created but when the product is out of stock it becomes a content pages with information about the product and the ability to order later if required (always a great place to cross sell)
Lastly we look at how many clicks in takes the user to buy the item, for example if they have to click womens, accessories, other, belts, their item and then purchase they've got to be showing real intent for purchase. In some cases it's best to raise those difficult items closer to the top of your site.
Our adwords campaigns also play a small part in this decision too, depends if you're running those or not.
Sorry it wasn't a very concise response but hope it helped in someway!