How do you override an override and not lose it on update? How do you create multiple different overrides of the same view?

Welcome to the world of Child Templates.

A child template works exactly the same as any other template except that it uses all the code, php, css and javascript, of its parent template. At its most basic level it only contains a single file, templateDetails.xml, as everything else is inherited from the parent. 

Now with a child template you can customise an override or css and keep the parent template as clean as the day your template provider supplied it. There is no limit on the number of child templates that you can create so each one could have different layouts and style.