I've been an off and on QRPer since the 1970s, when as a novice I used an HW8 (or was it an HW7?) to operate from summits while backpacking all over California long before I knew anything about SOTA (did it even exist then?).
Although I have a legal limit QRO station at home, I still love getting on the air during a backpacking trip with a lightweight QRP CW station - simplicity and fun; and I never fail to make QSOs.
My current setup is a TR-35 that I built from a kit; the entire station weighing about 2.4 pounds.
72,
Marco, AA5ET