Yes it is true that Galen did not carry a lot of camera gear; he carried maybe one or a couple camera bodies (frequently his lighter "amateur" nikon cameras) and several lenses. He often went with either a very small tripod or no tripod at all, and tried to use methods to prop his cameras up to keep his gear weight down. Also keep in mind that 35mm is/was generally the smallest acceptable (film based) camera format to yield good photographic results.
Galen also designed some of his camera pouches, cases, and lens cases which were later marketed by Photoflex (I have several) to protect his equipment and so he could have the equipment readily in hand.
Galen pushed the envelope as a photographer, taking photographs that almost no other photographer took prior or subsequent to him. I had the opportunity to hear him speak and meet him once (at one of the New Jersey Federation of Camera Club meetings) and took a photo workshop with his friend and fellow Outdoor Photographer Editor and National Geographic Photographer Dewitt Jones. But, it also should be noted that from what other photographers (who were familiar with his actual photos not what is seen in his books and the National Geographic [which were significantly smaller]) have told me, certainly some of Galen's work was printed larger than perhaps it should and had to be "really worked". Many of these images were not that sharp due in many cases to the lack of use of a sufficient sized or lack of use of a tripod.
Also, Galen's earlier work was shot on Kodachrome 64 (by todays standards grainier and not as sharp as some of the more recent E6 type slide films) and he knew his filter pack sets that he needed for his desired results. When he started to use the recent more bold and more color saturated slide films (such as Fujichrome Velvia) he had to relearn which filters he needed.
With the death of Galen and and his wife, Barbara Cushman Rowell, several years back in a small plane crash in California, Outdoor and Mountaineering lost one of its most prolific, best known, most loved photographers. Those of us in the field as fellow professional photographers, amateur photographers, the National Geographic, Outdoor Photographer, readers, etc. were stunned at his death being he was so close to home and considering the chances that he had taken in his climbs, visits to places like Tibet, and his many bush pilot flights in places like Alaska.