The conditions you mention in your original post seem similar to what I usually experience on my spring Sierra backcountry ski trips. I use an MSR Simmerlite. My cooking style is very simple - I only eat meals that are add boiling water - no simmering or anything. I light the stove once in the morning and once in the evening,melt (if needed) and boil (or just heat) what I need. With that in mind, what I have found is that if I am melting snow, I need about 3 oz per day for one person, and 4 1/2 for two (by weight). I have also found that when I find water and don't have to melt, it is indeed about half that fuel usage. This is based on a number of years of keeping track. So I would think that if your meals are similar, 4 oz per day should be a safe bet, should give you plenty. If you need to simmer or anything else, then add to that.
But what may not be relevant is summer usage, unless your meals are identical. In my case, I don't eat hot breakfasts or have many hot drinks in the summer, while I do in the snow. So my summer fuel usage would be significantly less per day than my non-melting snow usage, and thus if I doubled my summer usage I would not have enough for melting.