If you excelle at CAD but not engineering why not be a CAD modeler at a design firm or even in corporate? For example Apple often posts jobs for Design CAD Modelers.
Or if you really want to stick with ID then either develop your weak points or find a design job that caters to your strengths.
Not being able to get a job as a designer so teaching design seems like it would be frustrating for you and a disservice to students who are paying a lot of tuition money. If I was paying that tuition I’d want to know the instructors are there because they want to be there not out of circumstance. I think you can find something if your push yourself and you are open to location. I’ve moved across the entire country 3 times. You have to go to where the opportunity if you value that.