Rankings would need to be separate.
If you win SOTW, your skill is relative only to the skill of those who entered.
If you do well in a challenge presented by one of the more experienced artists here, the skill is relative to OURS.
Classing is a bit of an impracticality until there's a wider range of skill here. Not to mention that there's maybe two people here who would even be considered credible in their opinion of classes.