After searching the forum and experimenting some w/ the renaming function I was able to cobble this together: {filenamebase: 4,50}. It is not perfect. I could not find a way to either find a text string or a variable that would identify the length of the string and exactly specify how long, however; I counted my longest string and used "50" which was a number larger than the longest string without adding spaces at the end and properly renamed my filenames.