Get 'full-width' class on category template?

Howdy,

I’m trying to get some of my categories to behave like full-width pages. Removing the sidebar still leaves the page with the default .site-content width of 65%, so there’s just a gap where the sidebar would be.

The .site-content width changes to 100% if the body class is “full-width” but the body class is set through functions that are somewhat beyond my understanding. Removing the sidebar is apparently not enough to change the body class to “full-width,” and it looks like that requires inclusion of the template page “front-page.php”… is there a way to do that? Or some other way to change the body class within the category template page?

I could create new classes and monkey it myself but it would be easier if I could just get it to use the existing “full-width” class… any ideas?

Also, YES, I am using a child theme.