The reason I'm embarrassed is that in thinking of if I should redo the Instructable, I thought of an entirely better way to tackle the problem. I'm going to leave that instuctable there, because it's still useful if you need to make a shield TODAY and you don't have male headers.
If, however, you can afford to wait a week to get some male headers from the internet, this is by far the better solution. It's faster to make and more robust (and it still handles the offset header)
UPDATE: The headers in the picture below are soldered onto what most would consider the wrong side of the board. I've added a step (step 6) that shows how you could get these headers on the correct side.
Step 1: Required Materials
2 x 8pin male header
2 x 6pin male header
soldering iron (& solder)