It isn't possible to make a structure bigger than 64x384x64 under 1 name, but you can avoid with multiple structures, I could make it so it would detect for a especifc syntax in the name to load a bigger structure, and the same way to save.
I'm not sure, but there's always a way.
You can use the original structure block and download a "export/import" texture pack. (Does not work for console and realms)
You can use the original structure block and download a "export/import" texture pack. (Does not work for console and realms)