Yes, one thumb on each side works great in landscape mode. Eventually I'll have to add some UI feedback to this mode when toggling it on or off, which shouldn't be too hard to do with a little CSS since the trackpad and button are just div elements overlaid on top of the canvas.
I don’t know if multi-tap functions are already spoken for, I’ve only played with this a little so far (great job btw!). I think being able to toggle Trackpad Mode with a three-finger tap would be a nice _touch_.