Go heavy on food, water, clothing, shelter and ammunition. Minimalise everything else. After all, the only reliable method of bugging out is on your own two feet. And it's amazing just how fast the weight mounts up.
I had the following distinctly unsettling through the other day:
At 60 mph, a 30 min journey puts you 30 miles away from home. That's a two day march. If your lucky. And I would not care to presume on the kindness of strangers for shelter and food. Not to mention LEO's. There is a very good chance that you will get busted for vagrancy. Irrispective of circumstances. If the local ordinances say that vagrancy is whatever the local LEO's say it is, then you are in a pot of trouble. That sound like paranoia. Perhaps it is. But its better to be paranoid than wind up in a cell.
Also: pop over to Don Reac's site and read through the artical on being homeless. Required reading I would say. <img src="/images/graemlins/grin.gif" alt="" />