Highway 58 from Bakersfield to Barstow, then I-40 to Needles and south to Lake Havasu are all in snowbird country. Very mild winters with low likelihood of encountering sub-freezing overnight temperatures. No need to winterize for this route, or I-10 either (which is longer and less scenic).
The coldest area you will encounter is probably going through Tehachapi, which is in the mountains and may have frost or infrequent light snow. However, this usually melts right after sunrise. Also, the overnight temperatures are not low enough or of sufficient duration to worry about pipes or water freezing, even if you camp there.
We drive this route a couple of times a year and have never encountered weather that would require winterizing.