Winterizing, Etc.

As our first Northeast camping season with our 2720 winds to a close, the subject of winterizing the fresh water system has come up. According to the manual, essentially all you do is make sure everything is drained, which I have done. Some of my camping friends state that all of the water pipes must be filled w/ antifreeze, and that there should be a water by-pass for the hot water heater to accompliish this (so as not to introduce antifreeze into the HW heater). I find no such by-pass. Any suggestions?, or is it really necessary.

Also, has anyone had a problem with mice infestation into the TM during the closed winter months?