It looks like the hack might be to use <th> instead of <td>. I'm testing now, but it's stacking in the Outlook app in IOS now. Now I am checking that it didn't break in something else.
Update: if you're using ExactTarget, you can move your tracking code out of the top of the email (<custom name="opencounter" type="tracking">). This will prevent the tracking pixel code from showing up in the preheader.
I also have been adding a bunch of after my Preheader text, so it will not tag on any HTML code to my Preheader text. Kind of a hack, but seems to work.
LESS/SASS for email dev seems like it would slow you down. And for building sites I don't usually use it for small projects, but I've worked on large projects with multiple developers and LESS/SASS really helps. The organizational aspect of it was the key for me. To have one style sheet with thousands of lines of code is so hard to navigate. And, I did not have a choice in the matter, so I was forced to use it, but glad I did.