Okay, this is absolutely an admirable cause, and the support vehicle definitely makes a difference, but please do as BleekerStGirl says and get in long rides for several days in a row, just so you'll know what you're in for.

And the suggestion to buy shorts from different makers is a great one.

I hope you have a great trip. It will either be one of the best experiences of your life, or one of the worst. Here's to the former.

Roxy