As others have said, you could use
which will, in combination with
display invisible characters.
Now, there isn’t an explicit option which you can use to show whitespace, but in listchars, you could set a character to show for everything BUT whitespace. For example, mine looks like this
so, now, after you use
everything that isn’t explicitly shown as something else, is then, really, a plain old whitespace.
As usual, to understand how
listchars works, use the help. It provides great information about what chars can be displayed (like trailing space, for instance) and how to do it:
It might be helpful to add a toggle to it so you can see the changes mid editing easily (source: VIM :set list! as a toggle in .vimrc):
noremap <F5> :set list!<CR> inoremap <F5> <C-o>:set list!<CR> cnoremap <F5> <C-c>:set list!<CR>