Zoom to 1st person
Use the mouse wheel zoom to zoom to 1st person view when zoomed all the way in
To make it quicker and easier to switch between 1st/3rd person, just have the mouse wheel zoom go all the way in to 1st person instead of stopping at the back of the head. when zooming out, switch to what ever was the last 3rd person view used. Then remove 1st person for the home key list making that list shorter and and simplifying finding the 3rd person view you want.