Money and patience will be two of the most important things to bring out on the road.
Three categories of stuff come to mind. Personal belongings, business tools and vehicle tools. This list is, by no means, all inclusive so other folks have a chance to include their favorites.
Business tools you'll need include:
Paper or electronic record keeping materials,
Road atlas and or GPS gadget,
Envelope/stamps, BOL's,
receipt container,
clipboard, pens, notepaper,
DOT regulations , Hazmat guide, placards/holder
Personal belongings
Clothing for 7 day minimum (laundymat on weekend)
Reading material,
Cooler, portapot,
Satellite radio, TV/dvd player
Truck tools
Reflective triangles,
Flashlight,
Toobox, with spare of each lamp type, and each fuse type
One each of all your filters
B:C Fire Extinguisher
Duct tape