How unreliable is your bike? I wouldn't bother with spare plugs, it's not like its an old triumph where you run the risk of flooding the engine (and it would be quicker to wait for it to dry than try and change the plugs anyway!!!)
The main things of TDMs that I can see is battery (mini jump leads), coils getting damp...but there's not much you can do about that other than water displacer. Then I would just take the standard things bulbs, cable ties and gaffer tape, and some self amalgamating hose repair (but only if your pipes are getting old). You might want to consider chain adjustment, depending on how many miles you intend doing, I just took the sockets, and a couple o 12mm spanners, with the view that someone somewhere would lend me a ratchet...but I never used them)
I would however take pliers, hex keys (for lose fairing panels etc), I also had a leatherman...but really not much else IMHO.
The main things of TDMs that I can see is battery (mini jump leads), coils getting damp...but there's not much you can do about that other than water displacer. Then I would just take the standard things bulbs, cable ties and gaffer tape, and some self amalgamating hose repair (but only if your pipes are getting old). You might want to consider chain adjustment, depending on how many miles you intend doing, I just took the sockets, and a couple o 12mm spanners, with the view that someone somewhere would lend me a ratchet...but I never used them)
I would however take pliers, hex keys (for lose fairing panels etc), I also had a leatherman...but really not much else IMHO.