Latest finding about Revealing the whole XXL map = crash upon loading

Basically, there are 5 ways in total to reveal the whole XXL map, they are
1. Heroes' vision (by walking through the whole map)
2. Skyship (The wonder of Tower)
3. Cheat code
4. Erm
5. Cartographer

I wasn't able to test the 1st as obviously it's too time consuming. But for the rest of them, an interesting finding is that the 5th, cartographer (with all 3 types) can safely reveal the whole map without a crash upon loading.

Download for examples: XXL Map+savegame revealed the whole map without crash

At this point, the way of revealing a map can be distributed into ethical and unethical ways. The ethical way provide a safe way of revealing the map, while the unethical way is dealing with the devil.
Ethical: Cartographer
Unethical: Skyship, cheat code and erm
not sure: Heros' vision

Another interesting finding is that if a map has been already revealed by Cartographer fully, it does not matter if it's revealed by unethical ways followed by, the savegame will still be safely loaded.

Now return to fixing the crash of XXL by revealing the map. A possible approach to solve this issue is comparing the difference between Cartographer and other ways. The might be enough to tell the answer.
Alternatively, assuming that revealing the map with heros' vision is an ehical way (very likely), the only thing needs to be fixed is Skyship in normal gameplay without cheating. A simple patch changing the effect of Skyship (for example, reveal only a fixed range) could resolve the crash problem.

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Edit:A more interesting fact is that even with an unethical way for revealing, pass a turn and then save/load will also become safe.
This might be the best way to avoid crash before a real solution comes out.