I've read some bad comments about attaching a heat pad to the pan - even some name brands do not shut off when they reach a temperature high enough to be dangerous.
Water is safer since the large volume isn't going to boil.
Water is the only way to get the cylinders warm.
Bill Jenkins 40 years ago: use QD and large hoses to connect hot water from your truck to the race engine. Great for that 1st start-up.