In 1998 several of us operated from 'The Boulder Field' high on the shoulder of Long's Peak in Rocky Mountain National Park. Batteries for the operation were carried up in advance, and we operated using an ICOM IC-706 and a Perth Plus short vertical. We operated almost exclusively CW and did fairly well. The principal operators were K0IW, K0DUG and AC6SL. Others operated briefly or humped gear. The operation resulted in an article in the December 1998 QST, 'In the Shadow of a Diamond'.
Pictures from the operation are here
In 2000, K0IW and AC6SL revised the plan and mounted a lightweight QRP operation from the very summit of Gray's peak at 14270'. The operation was conducted exclusively in CW using AC6SL's recently completed Elecraft radio and a single battery. The antenna used was a simple inverted V fed by ladder line through a tuner supported by a telescoping carbon fiber pole. The pole eventually shattered at one point, but the operation still resulted in a seventh place finish.
In 2002, K0IW, AC6SL and K0DUG mounted a similar operation from the summit of Mount Elbert, the highest peak in Colorado at 14,443'. The operation was once again CW only, with the same antenna and radio. The operation did well, and also resulted in a QST article. Some pictures from the operation are here
I have a great passion for operating under difficult circumstances and Field Day affords the opportunity to do that. Colorado contains some very beautiful high peaks and it is a rare privilege to mount an operation here.