Drips, containers, and freezes

i have 2 zones that have drip irrigation going to planters (clay pots, concrete urns, and brick raised planters/boxes). I’ve got some tropicals, azaleas, and other shrubs and perennials in them. live in the Dallas area, so it’s below freezing here maybe 8 hours a year.

i’m reading that it’s actually good to water container plants before a freeze to help insulate the roots. but i’m also reading how a freeze will bust your tubes and fittings if water’s in them.

i was going to set up an IFTTT to start watering around 40d, then shut off at 32d. but the system would be full of water and wouldn’t have time to drain. of course, if the system is running and water is moving while it’s below freezing, the water wouldn’t ice, but if that 8 hours of freeze happens all in one day and i’m running it for that long… that seems like a small disaster.

any thoughts on how to handle this kind of dichotomy with the system? is the system freezing not such an issue with as few freezing hours that i have (and it never gets below about 15d)? is watering the plants then a bad idea anyway?

actually i just looked it up and we have an average of 33 freeze days, and our record was 295 consecutive hours of at or below freezing temps.