I'm not even sure that this is what I need. I'm using a custom post template, so for related posts plugins, when I select select show related posts below the content, they show up at the very top of the page. So I either need a related posts plugin that supports custom post templates, or need to find out how to add a sidebar above the footer/below the content. I'm using gazpomag theme.
I've tried adding a related posts widget to the sidebar, and then edited the css, but as all the posts are different lengths, the related posts are either too far below the content or overlap the content.