it's not just fluids you need to intake. You should be ideally eating 150-250 cals per hour for these rides longer than 2 hours. Fluids is only like 20 of those cals.
Nuun tablets are cheapish and easy to bring along. Also can get used to gas station foods/drinks. A lil more sugary but still work when on 2+ hour rides.
In another empty tube of Nuuns or zip lock, I put a bunch of Gu Roctane electrolyte capsules. These are clinch on super hot days, 2 per hour is my baseline. Start them early into the ride as it does nothing if your already near the point of cramping.
https://guenergy.com/collections/cap...olyte-capsules