What's interesting is you can find photos of individual aircraft with the de-icer boots on and then gone so it was clearly on the fly so to speak. Here's the well known 303rd BG B17F "Knockout Dropper" from above showing all the de-icer boots gone.
The more I look at the F models the more I wish we had em in AH too. It's really the 'classic' B17 look to me, and they flew much combat in the Pacific which the G models didn't so it essentially wipes out that source of skins, as well as the early ETO and MTO F models like Knockout Dropper.
