Given the popularity of the cemetery categorization effort and the fact that lots of people are asking this same question it seems to me that this would be a worthwhile project, despite the effort. I don't think you'd even have to include a burial date field or do anything more than use it to create the cemetery categorization. The way you have to categorize now is not at all intuitive and simple so most people are just not going to do it. Your cemetery categorization participation would explode if you add burial location as a new field.
