I have ported over (with the help of WPMU Support and some hired help) a lot of the functions to the front end with shortcodes. In my specific situation I don't have very tech savvy instructors and needed to make everything as simple as possible, and as designed as possible.
Again, my situation is fairly specific in that we offer 1 course that many different businesses offer to their staff. To facilitate this I have created a "master" class and we clone it each time a new businesses registers. Again, this part is fairly specific but I used ContactForm7 to create a registration form that the business fills out and am saving that data into a custom post type. Using the logged in user's email address I tie everything together.
Upon submitting the form (which auto fills the logged in user's email) they user is forwarded to a page with the new shortcode. All the shortcode does is generate a button the user clicks. When clicked, it clones the "master" course (based on course ID provided to the shortcode) and assigns the logged in user as the instructor. It also pulls over some data from the custom post type created earlier, specifically it changes the name of the course to the business' name.
Once the course is cloned and setup I am forwarding the user to a page with the Student Invitation functions. This shortcode finds all courses the logged in user is an instructor for and provides a select menu if there are multiple. Then it simply contains the same fields for invitation as the back end does, first name, last name, and email. Upon submit the button disappears and the success/error message appears. Once the user selects the fields again the submit button returns allowing the instructor to continue to invite as many students as needed.
I also added some code found on WPMU Support that allows the Instructor to view each student's workbooks. With some basic styling and some bootstrap functions it works really well.
With all of this, others could flesh out their course systems, keep the styling under control and potentially better serve their instructors. Since this is a lot of code, posting it here could get messy. I would be happy to email it or store it somewhere. I'll provide some screenshots to help visualize the workflow.