Auto Populate Category without displaying on page

Summary: Set the Category on the "Ask a Question" page without displaying the Category field. 

Content (required): We have multiple "Ask a Question" forms on our customer portal that are used for different customer segments when they submit a question. One segment only has a single category that is associated with them, so I want to be able to set the Category field on that page without having Category field displayed on the page. 

I've tried using the ProductCategoryInput widget, however the "hide on load" attribute says that the "hidden field will not be included during form submission. I'm wondering if there is another widget that I can use to set the field value for Category without displaying it.