Allow custom date formats in Supertile

I want to be able to have a single string in my super tile that is centered and shows the time and date together. At the moment the closest I can get is to have two date/time elements next to each other, one right justified and the other left justified. This looks ok/worse depending on the day of the week.

If I could specify the date format string I could get the tile to always look good with the value where I want it.