I'm not an electrician so please ignore what I say
But couldn't you just swap the breaker for a 20A, terminate both ends of the red and wire the receptacles in series as normal? I don't think the wire size would be a problem as long as the receptacle could fit it.
I'd agree with running a new homerun if at all possible. On the off chance you or someone else ever had an issue better it's done right to begin with.
-spence
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