I'm not sold on this idea, but I'm really not sold on the idea of storing dates (which aren't instants in time) as a timestamp, so here's my suggestion.
Convert your date into a human-readable integer (e.g. 2014-11-3 becomes 20141103) and store this integer value. It contains exactly the data you need, is simple to create and parse, and takes up minimal space. Additionally, it is ordered and has a one-to-one mapping of dates to valid values (granted, invalid numbers are possible, such as 20149999, but these are easy to detect). In contrast, there are approximately 86400 valid timestamps that represent each day.
NB: There is a discussion on DBA SE criticizing this method of date storage, but in that context a specialized date type exists, which obviously isn't the case here.