I carry a couple of spare headlight bulbs. That's all I've needed in 240k miles in 20 countries on 12GS's. Doubt that anyone can guess what is going to break. You will end up carrying 40+ pounds of dead weight. Save your money for petrol.
ride till you can't.
Boxer Cup Replika/red-white-blue
Cagiva Gran Canyon Italiano/rosso...for sale
Honda CL 360/orange...for sale