That's great, Catrin. I have solved the "should have" problem when I hike, by always having a tube of Nuun, Lara Bars, a hat, etc in my backpack. It's my real backpack that I take on more than local hikes or walks. However, I also have mini versions of this in my waist pack.
Your post reminded me that I haven't done any real hiking since early spring. I am trying to ride more this year... the tic forecast is horrible here, too, although I have never been one to not slather myself in DEET!