The idea of using a hydrogen filled balloon to lift a wire antenna to extend radio range is neither far fetched nor new! It was used during and after World War 2 in the U.S. military's SCR-578 (Gibson Girl) emergency radio transmitter. The radio was packed as part of survival equipment in large aircraft and was intended to help in locating survivors of a crash. In addition to box kites, the radio kit included balloons, and hydrogen generators to raise a wire antenna. Probably not a practical idea for a backpacker but at least not completely impossible either.

http://www.questmasters.us/GIBSON_GIRL.html

http://www.wftw.nl/gibsongirl/gibsongirl.html