Well, we've had roughly three or so days of hard and constant freezing weather with the temps down in the teens and twenties during the night and more than one night with some fairly strong wind blowing through.
The water coming into the camper via my insulated connection never froze.
The water line going to my toilet on the other hand froze last night. I just finished thawing it out and redoing its insulation.
I'd pulled the insulation earlier in the month to replace the shoring block under the shower floor (The old one had fallen apart, it was made of several 1x2s that had been glued together, there's a nice solid piece of 2x3 in there now), but I guess it never sealed back up well when I reinstalled it because I had this insulation present during the winter of 2008 which had constant cold wind and temperatures staying in the teens and the water line to the toilet never froze up back then.
So, I pulled all of the old pipe insulation after thawing the water line with my heat gun and then installed some new thicker pipe insulation and then wrapped it in a reflectix-based insulation tape to make it as insulated as possible.
The reflectix is a shiny foil sided insulation and works well at reflecting cold away from the line and also reflecting its own heat back in on itself.
With luck, the water line shouldn't freeze up again.