I had a thought. I know it will take up a button worth of space, but I was thinking about a compass in the bottom right. That way, you could move and fight (attack would be the center, then the direction) without having to use the buttons, if you wanted to play all stylus.
Just a thought, something like this: (stolen, not drawn!)

(Although a basic 4 point with a center button would be better)
Just that hitting the "a" and then using the direction pad (and sometimes the pad registers twice) can be a bit awkward...

desiv