Sleeping bag: depending on the type of backpack Witt has it could possibly be attached using some of the buckles & straps on either the front or bottom of the bag. Or if those are not available you could squeeze it between the body of the backpack and the top of it (often referred to as the Brain). Be sure to affix the sleeping bag securely onto the large pack so that it doesn’t fall off, and keep in mind that some airlines will not allow your checked luggage to have things hanging off of it. If that ends up being the case Witt can just check the sleeping bag separately, pack his entire backpack inside of a large duffel or as a last resort just carry it on the plane.
Another tip is to use a compression sack to pack your sleeping bag to reduce the size.
Lonely Planet: Nope, you don’t need to bring it. We won’t be using it much and we have some copies in Tiquipaya that you can use if you want.