Hard as she tried, Jennifer Garner couldn’t keep it together. Filming scenes for the new HBO comedy Camping — about, yes, a family camping trip gone awry — often “turned into uncontrollable fits of laughter,” says the Golden Globe winner. “Honestly, I felt there were moments of deep unprofessionalism.” But Lena Dunham’s limited series (premiering Sunday, Oct. 14, 10 p.m.) also brought on moments of deep satisfaction. “It was a light, happy experience,” the 46-year-old recalls to Us. “It’s good for you to laugh for 12 hours a day. We really were on the edge of getting ourselves in trouble all the time.”
PITCHING HER TENT With her own brood, the great outdoors proves to be, well, just that. “I’m a big backyard camper,” says the mom of Violet, 12,…