Tent-hunting at REI, Jackie Von Feldt and her friends lamented that they choke inside booming Denver and were preparing an escape. They wanted peace, and calming views, with room to roam and starlit night coolness they could savor in silence. So they pored over an array of ultra-light shelters for a trip into Colorado’s mountain wilderness that, hopefully, wouldn’t entail too much traffic. “You definitely have to leave the city.