"best practice" would be to unplug when not moving; rational being to prevent a draw from the trailer side from killing your truck battery or an over voltage scenario on the rv side from back feeding the truck and causing damage.
shore power is providing a charge voltage to the rv batteries which doesn't harm your truck; now if that were to fail and you were to get say 110volt to the rv battery I don't think that would necessarily get back to the pickup but I wouldn't want to try it
personally; my concern is around drawing voltage from the truck to the rv and being unable to start the truck; that is the scenario I'd worry about