Dehumidified Defrost needed?

NoCar340 said
What about an electric exhaust cutout? Pricey but effective: Already designed to divert from one outlet to another, available in multiple tube diameters, and flip-of-a-switch ease.
Don't want to spend that much? Mr. Gasket #5424 is a manual one, but it limits you to 2" diameter tubing. Apparently JC Rip-me isn't selling their $20 versions of the Mr. G unit anymore (at least not that I could find).

Now that’s a good idea!
What about one of these? Or two of these with a switched vacuum solenoid? Would open one/close the other…