The 3 canisters that come with most tyre repair kits are designed to put enough air in the tyre to get you to the next servo for air. They achieve that no problem in normal circumstances, if touring with the added weight take some extras. As for tyres get some decent new touring tyres on before the trip and forget about them, maybe a set of pilot roads 4 or 5 , whatever there up to now. Another thing that's worth taking is a roll of gaffa tape, can fix anything with gaffa tape, I never go across the nullarbor without it
I have a Held bright orange over jacket, great bit if kit, waterproof and breathable. Have relied on that as my French fluro jacket though never needed it in that context. Does it necessarily need to be yellow? They do a yellow version but I thought the orange stood out better.