Just like stated above, keep it centered. Being a rocker board, you won't need to set it back to ride powder either.
As for width, find something comfortable, but make sure it's now too narrow.
And angles, again, find something comfortable. Go for a duck stance for sure. You could always find a pro rider about your size whose riding style you like and see what their settings are. Try as many angles and widths as you like, you will always hear pro riders saying they switch it up all the time.