How to create single custom post type template for multiple posts/categories


I'm using your Custom Press plugin to create a custom post type, called Courses. I have several courses that each have multiple chapters (usually 8-12 chapters). Setting up the post type was easy, and I set up the the categories for that post type, as well as the custom fields I needed. I then created a single-courses.php template and that worked fine too. But here's where I hit a roadblock:

I would like to use a single template for all of the various courses, with the categories for each course showing up in the sidebar for that course. Same goes for any custom fields, to display with the associate course.

I know I can create category templates, and even multiple single-xxx.php templates. But is there a way to accomplish this with just one course template for all courses, using a query of some kind?