I use evil-leader with leader on space bar. For vim commands I type : and for Emacs commands I type SPC then :
For SPC leader to work you have to be in normal mode so no worry when typing in insert mode.
ALL my shortcuts starts with leader by pressing SPC with the thumb, then I type a sequence like 'fs' to save the file. I switch back to normal mode by pressing 'fd' while in another mode (I don't use keychord anymore which is a false good idea, I have a custom script for this).
You can see my shortcuts here: https://github.com/syl20bnr/dotemacs/blob/master/my-keybindings.el
I truly think this is the best you can get by combining two wonderful pieces of software: Emacs and Vim.
This have numerous advantages like giving you a big space for shortcuts and be able to produce NATURAL key sequences which are easy to remember.
The main downside (and only to my mind) is that you have to learn Vi first (as mentioned in Sasha drawing).