Hi, SK. Hopefully you aren't taking any opiates, which are the classic bowel slowers. In any case, I'm not sure that focusing on transit time is necessarily the best focus. None of us can turn off bowel activity at a particular time by scheduling meals, and it's not like the whole meal shows up at once. Those of us who sleep through the night are mainly benefiting from increased pouch capacity, I think. This takes some time and practice, sometimes called "stretching the pouch." Experiment with delaying your bathroom trips a bit (while awake) and getting used to the signals from your body.
Regardless of how much water you are drinking, use urination as the signal of sufficient hydration. Are you peeing light-colored urine at least 3-4 times per day?
One other thing you might try: Psyllium fiber is mostly used by J-pouchers to thicken up output, but it's worth remembering that it's mostly used by the rest of the population to gently treat constipation. It might not help you, since it bulks things up (and your pouch capacity sounds insufficient already), but if your output gets too firm it can soften bricks as well as thicken liquid.