I miss the console terminal where Alt-F# directly selects a terminal by index. So:

    bind-key -n M-F1 select-window -t :0
    bind-key -n M-F2 select-window -t :1
    bind-key -n M-F3 select-window -t :2
    bind-key -n M-F4 select-window -t :3

    bind-key -n M-F5 select-window -t :4
    bind-key -n M-F6 select-window -t :5
    bind-key -n M-F7 select-window -t :6
    bind-key -n M-F8 select-window -t :7

    bind-key -n M-F9 select-window -t :8
    bind-key -n M-F10 select-window -t :9
    bind-key -n M-F11 select-window -t :10
    bind-key -n M-F12 select-window -t :11