+1 on the hydration pack.

Even once you're acclimated, you still need to carry and ingest plenty of fluids, and a hydration pack is the best bet for that. I also find that I feel better on hot rides if I replace electrolytes. If you don't like Gatorade, there are other 'lyte replacement fluids on the market. I carry water in my pack and Gatorade in my water bottle, and plan a stop at a convenience store if I think I'm going to need more than that.