Is the reverse button usually hit with the thumb of the left hand?
Yes.
If so I could just include annother button on the bottom right corner of the joystick, as close as I could get, but like you said, that might not be close enough.
That would be the closest to the original layout.
What if I added annother button near the thrust/fire? That way you could just hit it with annother finger on the right hand.
I would mock it up first.
My first thought is that you're going to run out of fingers quick.
Never having played it though, you may not notice this as badly as you would otherwise.
My first thought for layout would be:
Index - Thrust
Middle - Fire
Thumb - Reverse
Ring - Smart Bombs
That would leave the Hyperspace button as one of your left/right Asteroids buttons.
You will reverse ALOT while playing, and need to smart bomb really quickly.
Hyperspace is a last ditch kind of thing, so moving your hand out of position slightly shouldn't be a big deal.
The best overall "classic" layout I've been able to come up with was:
D
J L R C B C
A
That let's you play Asteroids on the L/R-A/B/C buttons, 3-button games on the A/B/C, and Vanguard on the A/B/C/D diamond pattern.
I didn't like the extra buttons on the panel, and opted for modular though.