Not what you asked but thought I'd chip in anyway (been there done that....).
Go through your packs together before you leave home, so you know your friend is packing light. (This helped one of my groups immensely, on a pre-trip meeting, when I took my loaded pack and went through every item with them. One lady later told me that she threw out more than half the stuff that she was going to take with her.)
Check all the bus routes beforehand (they can all be found online somewhere), so you know where and when there is a bus option available. (That has come in handy more than once.)
Good luck!