The only thing I could think of, is moving Dispatch ahead of Mutilate, and removing the modifier from it's /cast options, it will make the macro always try to do Dispatch before continuing, and if Dispatch isn't able to go off, it will do Mutilate instead (or should, in theory)
And on the topic of keybindings, I have..
1-4
ctrl 1-4 (i have a Deck compatc-keyboard, ctrl is easier to reach on it than alt is, normally it'd be alt 1-4)
F1-F5 (again, compact keyboard makes those very reachable)
and shift-macros for most of those.
I also have Mouse Scroll up and Down, shift macros for those