Another Winterizing Question - Heater, Motor, Etc

This is the first winter than I'm planning on keeping my boat in it's slip in the Delta.

What kind of winterizing are people doing? I don't expect it to be big issue, I can drop a light or blanket in if we get a long cold snap. I understand that it takes a few days of consistently freezing temps to really cause a problem.

My bigger concert is the heater. I've heard some nightmares of the heat exchangers freezing and cracking and being a nightmare. Is this real or am I getting rumors blown out of proportion? If there a good way to insure this doesn't happen in a system that I don't want to fully winterize?

Could you put a blanket over it? You might be able to put a quick disconnect where it comes in from the motor. So when you get back just disconnect it and it will drain.