Just a quick update on this, the new 2.0 version requires 5 fewer Skystones, to speed things up. Thank you again for your helpful insight!
For now, they have been pulled while I consider how to best add a completionist bonus . I really like your idea, so in a future release I plan to bring them back in. Speeding things up took top priority for 2.0. I played a full, regular speed playthrough after your comments and realized you were quite right, the final quest needed speeding up.