Agreed. It takes days below 32ºF (don't know about them funny units you mentioned). Wind chill matters not a nit to the inside of a boat. Fiberglass don't sweat or exude moisture (wish it did!).
The rocking motion in a slip also keeps the water molecules bumping (friction - though miniscule) and further reduces the tendency to skim over and ice up.
Charlie P. P31-2 #80 CATNAP
To travel hopefully is a better thing than to arrive - R.L. Stevenson
I suspect that, if you should go to the end of the world, you would find somebody there going farther . . . - H.D. Thoreau