Tmux 2.4 (April 2017) added a very useful copy-pipe-and-cancel
command.
The config below configures copying to the tmux buffer and the Windows system clipboard in one command, including click-and-drag copying (without holding shift). I'm sure there's a way to get this to work with copy-mode
(emacs style) but I'm not familiar enough with it to offer any advice. I've tested the config successfully both in WSL via PowerShell and WSL via MinTTY.
# Configure copying
bind-key -T copy-mode-vi v send-keys -X begin-selection
bind-key -T copy-mode-vi Escape send-keys -X cancel
bind-key -T copy-mode-vi y send-keys -X copy-pipe-and-cancel "/mnt/c/Windows/System32/clip.exe"
bind-key -T copy-mode-vi Enter send-keys -X copy-pipe-and-cancel "/mnt/c/Windows/System32/clip.exe"
bind-key -T copy-mode-vi MouseDragEnd1Pane send-keys -X copy-pipe-and-cancel "/mnt/c/Windows/System32/clip.exe"
I was surprised by the lack of information available, glad my post was of some help. Thanks for the default key binding additions!