Quad Texture - Make Texture turn White

Hello,

I have a Texture2D applied to a quad within my 3D scene, using the shader 'Unlit / Transparent'. I want to be able to give user feedback when a user clicks on the texture.

The mechanics of the click is all there, I just want to be able to change the texture style/material style by changing it all white when the user clicks on it, and then back to normal when click is over.

My first thought was to create the same texture, but just fill it all white within photoshop, but that means doing it for all my clickable textures, which will result in double file size, which isn't good. Just wondering if there is an easier, more optimised alternative?

Thanks