Improve dynamic date & time filtering

I have a dataset that has a date field, and I need to be able to dynamically select or unselect dates. For example, each row has a field containing either a blank or a date. I want be able to filter rows that are either blank or fall before a time 30 days prior to now. At the moment I have to use Advanced Filtering to select either Blank or "before a date 30 days prior". Please could you add the facility to dynamically select "all dates before 30 days prior" + Blanks, which would mean I wouldn't need to manually adjust the date each time I run the report.

Also, it would be useful if the Relative date filtering also included the options: "is NOT in the last", "is NOT in this" and "is NOT in the next".