I just finished my thru hike of the AT last week.
I never used repellent.
I never used sun block.
I did not use a filter nor drops. This caused quite a bit of controversy, so I didn't advertise.
I went with Andrew Skurka's advice, plus I have lived off of a glacial cistern for 20 years.
I did have a Hennessey HyperLite.
I used an UQ in GA, but I then sent it home.
I used only my i-phone.
I uploaded when I had wi fi to YouTube and embedded the vids.
I tried a Power Monkey, but they sent me a replacement when I got home. Go figure.
Honestly, I only know of one other hiker who went ultra-light ( 16 pounds) and he admittedly said it was stupid. I saw no reason to go so light. Especially when it snowed twice.
I had over 230 thousand hits. Pretty sure I journaled some interesting aspects.