If you are happy to toggle some items when you want to change to quiz, this way could be a simple route to achieve it.
I did this simply once with a course containing everything on creation. Started with Feedback quiz hidden (but created) and then just clicked on the eye symbol to hide the resources that needed hiding and the quiz made visible. This way is just one course and a simple thing avoiding settings and timings. Teachers can of see hidden and non-hidden items but students only the visible ones. If the activities panel etc still visible on that course, then can get to resources that way, but could be made invisible too.
You could do this at a higher level by hiding and unhiding topics using topics course style. Not convinced of need to change to lessons for your needs.