My solution to this is to use the Hyper Key + V as paste and match style.
The first step is to setup Hyper Key on your machine. Full details can be found here, Hyper Key Help - Keeping Caps Lock Functionality. This has the effect of making the caps lock key the same as holding down ctrl+shift+cmd+option.
Once this is working I made a keyboard shortcut for all applications. You can see the settings in the screenshot below.
Now I hold down caps lock + V and I have paste and match style by holding two keys down instead of four. Not the most elegant of solutions but it has worked so far. I agree with @carlsson that having paste and match as the default would be better.