Now I see what you mean. Unfortunately, this task is far from trivial, since the header cells were modified quite a bit. However, we have gone the extra mile and come up with a possible solution for this problem. The only solution I can think of is to save all custom elements that were added and all original elements that were removed in some kind of class field and then show / hide them according to the toggle button. I have taken our sample and extended it quite a lot in order to achieve something similar. Have in mind that this is not a full-blown solution, but it can serve as a foundation for further fine tuning. You may need to tweak it or add additional logic in order to tailor it to your needs.
I have attached the sample project. The places of interest are the Enable and Disable methods of the GridViewFilterRow. Basically, on Enable I show the custom elements and hide the original ones and on Disable I do the opposite. This should get you started. I hope it helps.
the Telerik team