Drink before you are thirsty. By the time you feel thirst in the desert you are already dehydrated. The morning routine should include a big glass of water before you throw a leg over the bike.
Carry water on the bike, not just in the hotel. A hydration bladder or large bottle in the tank bag means you can drink at every fuel stop without unpacking. Rehydration sachets are worth their weight — in 40°C you sweat out salts faster than plain water replaces them, and a sachet at lunch keeps cramps and headaches away.
And yes — the lesson from Day One still holds: visit the toilet before you leave the fuel stop. Your bladder and your riding schedule will never agree on this.