Agree with DD, my Thruxton is fitted with tubes and has tubeless tyres. My penneth worth, either seal the spoked wheels (quite involved) or pack a spare tube for front & spare tube for rear. Very unlikely you will be able to repair the existing tube. Mine went flat (small screw) rode bike for 15 yards or so to a safe place, ripped the tube to shreds. Of course you would need suitable tools to repair on the roadside. It is likely that even a tyre centre would have trouble locating the exact size tube for your bike. Tyre easily repairable unless a sidewall split. They are relatively inexpensive & easy to pack.
I wouldn’t bother with clutch cable, but if you do take one route it alongside the original that way it’s already in place should it be needed and saves carrying space.
Brake cables are you sure One thing to consider taking would be a spare clutch lever, if the bike falls over or you have an off and she goes down on its left side you can bet the clutch lever will snap and your stuck. If she goes down on the right side and the front brake lever snaps you can still ride, with extreme caution using the rear brake.
He could always use the molegrips Seriously though, if you're that worried about a modern bike breaking down on a 3 week holiday then maybe you should look at somewhere more populated. You can get way too hung up on 'what ifs' and forget to just enjoy yourself. If a 2 day delay for spares is that unacceptable to you then again maybe look at a safer trip as going more remote means potentially more unexpected delays or issues
Off to France and Spain in 6 weeks time and will be taking the same spares with me "just in case what if" And for the record when you have hotels booked no delay is acceptable.
I did and the demonstration was interesting but I am not a 100% convinced it was worth the £72 if you have tubed tyres. They reckon it is 95% successful on tubeless and 75% on tubed. They did a demonstration for me on the tube which did not have much psi and they admitted that if the puncture happened on the top by the join it is quite likely to split the tube. However it was impressive to watch it seal itself when a 3ml spike was driven into an inner tube. I was over at my Triumph dealership today getting the bike booked in for new tyres and tubes next Wednesday and the general consensus of opinion was it was not worth bothering with on my bike. To summarise I was impressed with the product but probably not for tubed tyres. I have a Honda that is going in for a service at the end of the month at the dealership that did the demonstration. It is tubeless and I am leaning towards having it put in the tyres as it certainly worked well on tubeless.