While you wait for 2.7 to deliver on new features in the PDF viewer to make letter sized PDF's more visible you can try this tool I wrote.
It utilizes the PDFBox Java Toolkit from
http://www.pdfbox.org. You'll need to grab that in order to use this command line tool.
It's written in Java so you can pretty much use it anywhere you can get java, a command line, and some PDF's to rotate and crop.
If there is demand I can put together a GUI addition to the tool for the command line challenged.
I'll put together more detailed instructions for running the tool later tonight, in the mean time, those with Java skills can have at it.