That would be the last thing I would do. For the same reason that no dealer in their right mind would touch any modification of the throttle pedal, adding this is just an invitation to trouble. Sooner or later it comes loose, jams the throttle and you've got a problem. Note the two pages of warnings in the owner manual about making sure the floor mats are properly hooked to the floor, the warning labels on the back of the floor mats, etc. These are in the manual because of past issues with the throttle pedal and brake pedals being jammed.
Which were entirely bogus with the Prius. No examples of anything but "operator error" or outright fraud. Toyota fell on its sword WAY too quickly. There is no way with proper mats properly installed that the pedal could get stuck. It was never a mechanical issue with Toyota's product. And they cut the bottom off my accelerator pedal :| Move your heel back an inch? Does your model have electric seat including height adjustment. I find the seat much more comfortable and adjustable than my Gen II seat.
That's what happens when lawyers and marketing people make the decisions. I don't like not being able to left foot brake, as they have the brake overriding the throttle now (another decision driven by the lawyers).
They made it so the brake overrides the throttle. I can left foot brake with no problems, but I can't trail brake with my left foot.