What kind of trip are you taking and how far. If you are on paved road, the TAT, etc it would influence what I would take.
Mostly paved I would subscribe to a towing service, carry a cell phone, and take little to no parts.
Otherwise: Carry some extra chain and master link(s), tubes and tube repair kit, air pump (manual or electric), a crutch (to lift rear or front tire off ground-simple to make), extra headlight bulb, fuse(s), stainless steel wire, electrical wire, connectors and electrical tape, schematic of electrical system, extra key, extra quart of oil. A good tool kit that you have used before going on the trip so you know that all the proper tools are there and work well to do the job. Good epoxy glue, super glue, small quantity of grease, chain lube.
On very remote routes I would take a shift arm, brake lever, extra gasket for left side cover and/or gasket material, clutch cable (taped to the bikes clutch cable so it is pre routed and ready for use) I have carried these for years and never needed them.
That's all I can think of for now.
All you need is Duct tape and a BF hammer.