CoursePress Pro feature request: lock a student out of all previous units in a course

I would like to be able to temporarily lock a student out of all previous units in a course if they are on a page in a unit that requires a mandatory answer. Currently it locks the student to the page within the unit. However; if a student clicks "save and exit" they are able to go through any completed unit in the course. This is not ideal if you want the student to take a "closed book" assessment. I am thinking that there could be an additional check box in the question elements settings that says "Lock Units: Prevent user from viewing previous units in this course until answer is graded." Thoughts?