One type of map—huge paper topos—existed when The Mountaineers first published the 10 Essentials, the club’s checklist of must-pack gear for any dayhike or backpacking trip. Nowadays, the options are endless. Case in point: These waterproof guides pack Webster’s-worthy detail into a pocket-size package for AT and JMT thru-hikers. Mileages, elevation profiles, water sources, and routes appear on one foldout sheet that weighs just four grams. The complete sets comprise nearly two dozen individual maps, so you just carry the pages you need…