For me the ultimate trick is to open the current prompt in vim with F2 (Ctrl+X ctrl+E seems to work too):
# Use F2 to edit the current command line:
autoload -U edit-command-line
zle -N edit-command-line
bindkey '^[OQ' edit-command-line # f2 is ^[OQ; to double check, run `xargs` and then press f2
> # f2 is ^[OQ; to double check, run `xargs` and then press f2
I remember using `cat -v` before learning that `xargs` exists… or maybe before `xargs` actually existed on systems I used :)