Paul's list is pretty complete. I would add the following:
clip leads ("I thought you had the T-Trak buss wires" - quote from our last get-together)
backup DCC system (NCE for us)
DC power pack and engine, because that's the ultimate fall-back for DCC failures (although we always run one DC loop anyway)
parts to build a "module" to cross at least a 1X gap, should modules not arrive or fail or it's just needed (I carry a Kato bridge, appropriate track to make 310 mm, and some 1 X 3s to lift the track)
spare modules, just in case
Geoff
