I seem to require a lot more water when hiking (and exercising in general) compared to most people. I also find that I dehydrate at a faster rate than others. Besides using supplemental things such as vitalyte/gatorade, what can I do to help my body stay hydrated?

I suffer from the same problem. I usually carry at least 2L while moving. I try not to ration my water and force myself to drink consistently. I carry the 2 part potable aqua, a coffee filter and an aqua-mira filter bottle. Never pass up a chance to fill.
While some may think 2L is too much weight to pack, it sure beats waking up in an ER with an IV force feeding you fluids. While this has never happened on the trail it occurred twice in the Army and once since. My own personal record is 4 units before I had to use the restroom. Some people can tolerate dehydration better than others.
BJ

"Besides using supplemental things such as vitalyte/gatorade, what can I do to help my body stay hydrated?"

I'd look more thoroughly into the subject of electrolytes for a start. Maybe consult a sports med physician. I don't know about Vitalyte, but Gatorade doesn't contain adequate electrolytes, IMO/IME. Without adequate electrolytes in your drinks, you run the risk of hyponatremia, potentially fatal, if you drink too much water in an attempt to stay hydrated.

I've found that even on relatively cool days I need to carry some sort of electrolytes in addition to water. If I start feeling dragged out or a little bit headachy, I sip from my Camelbak. If that doesn't improve the feeling while I'm still moving, I take a hit from my 20 Oz bottle that I usually have put some Nuun tablets in--1 tablet of cola + 1 tablet of lemon chai is pretty good! That often clears things up. If that doesn't do it, then it's time to eat something. I like the Nuun tablets because it's less bulk and weight than electrolyte packets, + lots less sugar.