What you said sounds about right to start with, the recipe, and yeah more water will allow the yeast to survive longer. If you find that recipe is not enough CO2, rather that upping the yeast, I would suggest going to a two bottle system, maybe two 2 liters with the same yeast:sugar. Having two bottles on staggered start/change time is easier to maintain a consistent, steady output over the long haul. Two bottles changing out one per week, for example.
That is the main thing you want to avoid - up and down levels. Just keep an eye on the bubble rate, especially with only one bottle. Be ready to make a new mixture the moment production begins to slow down....at all.
As for what bubble rate for x ppm, that depends on a lot of factors which vary from one tank to another. 1 bps would probably be a good starting point though.
There's a couple links in my sig that may offer some additional food for thought.
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