Okay, now I really dislike prolonging the already-overlong primitive discussion, but something about which I never thought, just spurted to the forefront of the mind.
One assumes there's nothing wrong with the primitive's hot water supply, as she anticipates taking baths in winter.
A bathroom without heat in the middle of winter's happened to me--not often, not here, and not recently, but it's happened.
Why not just turn on the hot water in the bathtub, and let that heat the room?
Now, maybe the primitive uses the bathroom at other times, times that don't include taking a bath. Such as when one goes in to sit down on the commode.
The primitive could rearrange her schedule, so as to sit on the commode while the bathtub's filling up with hot water, warming the room.
If the primitive's sitting on the commode more than twice every four or five days, or three times a week--it should be obvious I'm referring to doing a dump, not a spray--then she seriously needs to sit down and examine her diet and personal habits.