How to Reserve a Campsite, Even at the Last Minute Who says you can’t get a reservation for the great outdoors this weekend? The view from a site, bookable on the campsite sharing app Tentrr, at Fred Hayes State Park near Duchesne, Utah.Credit...Sheldon Martineau By Megan Michelson April 24, 2021, 5:00 a.m. ET Pretend it’s a Monday in midsummer. You live in or near a big city, a few hours from mountains or forests, and you want to go camping this coming weekend — a few days away. Before the pandemic, that may have been possible. But these days the outdoors and camping are having their biggest boom since humans lived in caves, and finding a last-minute campsite is about as hard as spotting wild glowing mushrooms.