Email Widget Editor - Add Sale Attributes for Preview

For a client setting up Email Product Recs widgets, one of the most common and most basic tasks is to set up rules for formatting UnitPrice and SalePrice for products that are on sale (reduced price).

But the widget preview in style editor doesn't allow to manually define a UnitPrice. Therfore it's not possible to test if price formatting/styling for sale products is correct.
Nowadays the only way to check is to create a preview in the last step.
But if you're using Reusable Templates, this is not easily possible. You have to jump out of the editor, into the widget campaign, create a preview and then going back to fix things. This is a huge pain!

The style editor preview should allow to manually set unitPrice, SalePrice, Discount and the $off attribute to allow proper preview of all variables important for displaying sale products.