Sadly I found the vim plugin mentioned not to be working with iTerm2 3.0.15 (to be fair I don't know if this broke on older versions) - but I found this hack instead.
Map command-p to do the paste and using iTerm2 vim keys. Obviously this only works for iTerm2.
How it works. I use "jk" to enter escape mode so you will also need:
:inoremap jk
in your .vimrc.
Then it just invokes P to enter paste mode, "+p to paste from the clipboard and then P to disable paste mode. hth.
