I'm not absolutely sure but I think it will be possible then it's only visibilty-properties. I have also xls-files which have uncertain data-positions and fieldnames. To solve this I read in an additionally (hidden) sheet the positions per xls-inbuild index() and address() functions but you need definitely some logic to find these data - maybe this could be an alternatively.
yes, it is possible (I have tested it) if the field is only made invisible.
Up to now, I have not encountered Excel_files with uncertain data_positions - well, it has always been sufficient as yet to have some flagfield highlighting the block of cells to be loaded for a certain purpose. I can usually convince the people populating Excel_lists to implement such a field as it's not much of an effort and it doesn't really disturb the look_and_feel - even less so when the field can be hidden.
Still, what you do there does sound quite awesome and I could be in need of something like that at some point. It has been a while since I've worked with Excel.