That's actually quite a feat!
I am ready to say my game is entirely unplayable without a mouse.
I'm a bit doubtful that orientation can fix this kind of an issue.The reload indicator is a good idea that i should add.
Until then, you can actually hold mouse to fire.
Holding the mouse key might not be a good idea when playing on a laptop, because some laptops disable the touchpad while you use the keyboard. (And they call this a "feature")