The branch circuit ampere rating directly correspond to the rating of the OCPD according to T210.24. So 210.23(1) is violated with a 20 amp breaker.
I know they are not common, but what about 25 amp OCPD's? or 35? or 45? I guess there are no rules for these. So the answer is to get a 25A breaker, use #12's and a 20A single receptacle with GFCI protection.
This install also requires a separate controller which could be a 25A ac only general-use snap switch. 430.83(C)(2)
and is a general-use snap switch an 'air-break switch'? If so, then you do not need a separate disconnect for the controller.--430.111
What was the question again...?
