Scott and I thought of it independently. I'll bet plenty of other owners have realized the value of a cooldown feature, especially those who pay time-of-use rates. Tesla says they thought of it, but couldn't figure out how to do it. And yet a motivated owner with no help from Tesla figured out a way to do it. I let you, kind readers, decide what the engineer meant by "significant hurdles."
Nice work to both of you. I guess this means they're really moved on from the Roadster and have no plans to add any features, even small ones.