How can I easily toggle the cursor size back and forth between normal and largest?
Perhaps this is too excessive but you could create an AppleScript which would toggle the size of the cursor. To do so just:


Go to System Preferences / Universal Access and check Enable access for assistive devices, this will let you use AppleScript to query and control the user interface of most Applications.
Go to /Applications / Utilities / AppleScript Editor and paste this code and save it as Application:

tell application "System Preferences"

    set current pane to pane "com.apple.preference.universalaccess"

    tell application "System Events"

        repeat until slider "Cursor size:" of window "Accessibility" of process "System Preferences" exists
        end repeat

        set theSlider to slider "Cursor size:" of window "Accessibility" of application process "System Preferences"

        set stash to value of theSlider
        if value of theSlider is 1.0 then
            set value of theSlider to 2.2
        else
            set value of theSlider to 1.0
        end if
        stash

    end tell
end tell