I don't know about any spreadsheet, but you can either call every day or call on your checkout day for all of your dates. For example, we are going to BWV July 7-11, then VWL July 12-15. I'll call for one on August 13 (since the 11th is a Saturday) and for VWL on August 15. It's not hard to figure out what 11 months is.
Robin M.