Jukite's answer is good. Also, since you're Kickstarter backer, you have Pro subscription with API Mods access. You can use the API Mod script called TokenMod to set up a Macro button that rotates a token. I have them set-up for Clockwise and Counterclockwise rotations. Some of my Players rotate with the handle and mouse, some rotate with the "E" and mouse-wheel, some of them use the Macro button from token-mod that i set up. It is still not a pure keyboard option tho (unless you make a simple Macro Name like #rotate and type that macro name into chat to trigger it)