So a house is needed - with all the associated inconveniences such as construction, development, etc.
That was the original statement from the fact checker user200. The word "house" is found neither in §17 nor in §20. Also nothing about development, etc.
An apartment within the meaning of the law is any enclosed space, it says there. That can be a shed, a barn, a garage, or a chicken coop. Or even a houseboat. So the thread opener buys a small sailing yacht, digs a garden pond, and launches the yacht there. Then he can live inside. Also in the registration law sense. By the way, someone actually did that in Bavaria.
Wasn't the corresponding picture even published here in the forum? I'm not sure about that.
And what requirements an enclosed space must meet is not stated in the law. So there are no requirements for it.
One doesn’t have to accept that the employees of the residents’ registration offices always interpret it conveniently for themselves. They also pass on data without the consent of the persons concerned just as easily.
Anyway. Basically, a porta-potty is enough for a registration address.