@svoelker: The Catch Mustang homepage layout has different sidebars and you have used right and left sidebars which will divide into two.
If you user Homepage Top Sidebar, it will take only 25% each widgets and layout is for 4 columns.
But if you want single full width content below your slider, then you don’t need to user the widgets. You can use Static Front page.
1. Create a page for your homepage from “Pages => Add New”.
2. Go to “Settings => Reading”, and select the page you created in “Front page”.
3. Go to “Appearance => Theme Options => Homepage Options => Homepage/Frontpage Settings” and click on “Enable Latest Posts or Page”
4. Then you can disable the sidebar that you don’t want from “Appearance => Theme Options => Homepage Slier Options”