As the OP said they're using Spreadsheet::Read, at this moment, only monkeypatching is a possible way out.
I will see if adding your own subclassed class to overrulle supported classed would be possible as an option. Currently it is not, as my wrapper checks on the class name, which would have to be changed to check if the parser used is a subclass of the supported parser. And of course it needs a new method to tell Read overrulle the existing parser.
boleary please add your request as feature wish to ParseXLSX issues and the wish to subclass parsers to Read issues.
Enjoy, Have FUN! H.Merijn