Laurie,
You might want to think about both sides of the water balance, and reduce the output as well as what inputs you will need. You can only really control how sweaty you get, and reduce your sweat output by walking at or below the point where you are actively sweating (if you are already doing this, you can probably stop reading now
). I know that if I am actively sweating, my body's fluid consumption can rise to just under 1li/hour. I suspect that it is around 100-200ml/hour normally during daytime activity.
You will still sweat (at least in normal conditions). Because you are outside and there will be a higher evaporation rate, you could be sweating more than you normally would and still staying dry.
I read up on this approach a few years ago, but a quick web search didn't find the resources I might have pointed you to about no-sweat and low-sweat walking techniques, but they revolve around adjusting your pace at the first signs of sweat not evaporating, ie damp patches forming under your arms or elsewhere.
I drink regularly, but use the onset of thirst as a trigger. You might not drink much in the first 1/2 hour or hour, but I find I drink regularly after that. The jury is out on whether to consume fluids before thirst, and for normal people, I think the evidence is that this isn't necessary. We are not sports people under intensive training or military operating at higher activity levels and heavier loads who might quickly develop a fluid deficit. The advice to these groups to drink before thirst might be justified, but I don't think that it is for the average pilgrim.
My view on sipping is that I take a reasonable amount when I drink, perhaps a 1/4 to 1/3 of a cup or more. Its hard to tell when drinking from a bladder. I know that there has been some research work on this, and there is a point where smaller sips become less effective when one is thirsty. I would recommend you take at least a mouthful each time, ie around a 1/4 of a cup, rather than really small sips that just moisten the inside of the mouth.
I always carry water purification tablets. I use the opposite approach to LTfit, and drink from the bladder first. If that runs out, I decant my bottle into the bladder. If I then have to refill from an untreated source, I use the bottle and add a purification tablet to that and leave it for 30mins or so. It can then be decanted into the bladder, and the process repeated. If you think 3li is your limit, I would use a 2li bladder and carry a 750ml to 1li bottle. This is on the basis that most purification tablets will treat up to 1li of water in 30 min.
Regards,