CBS and the producers behind the network’s new reality series “Beyond the Edge” were bracing for their celebrity cast to mutiny. They even had contingency plans in place, just in case their stars decided to give up in the face of grueling conditions.

“I remember in the middle of production, saying on multiple occasions, ‘I can’t believe they’re still out there,’” says CBS alternative series senior VP Mitch Graham. “You never know in a new format, what you’re going to get. We had an eight-episode order in place. My biggest concern was whether or not people would stick with it, and whether we could actually complete a series order.”

Created and produced by Renegade, the company behind Discovery’s long-running smash “Naked and Afraid” (and years before that, “Blind Date”), “Beyond the Edge” features nine celebs roughing it on an island in Panama, teaming up and competing in challenges to earn money for their designated charities.

Signing on for “Beyond the Edge” (which premieres March 16 at 9 p.m. ET on CBS) were “American Idol” alum Lauren Alaina, Super Bowl MVP Ray Lewis, country artist Craig Morgan, NBA champion Metta World Peace, supermodel Paulina Porizkova, NFL legend Mike Singletary, actress Jodie Sweetin (“Full House”) and television personalities Colton Underwood (“The Bachelor”) and Eboni K. Williams (“The Real Housewives of New York City”). (An undisclosed additional contestant dropped out because of the show’s vaccination requirement.)

“We wanted people that were really going to buy into this,” says executive producer Greg Goldman. “It’s one thing pitching and getting celebrities to agree to it. It’s another thing where we actually landed in Panama for pre-production and it’s 95 degrees out and completely humid. I mean, you’re just dripping non-stop.”

In an age of peak celebrity reality programs, Graham says it’s getting harder to cast stars — particularly for a show like “Beyond the Edge,” with its grueling physical demands. “There’s so many places for celebrities to do things,” he said. “What was tough about this one was honestly finding celebrities who would be willing to do it. Because it was real out there. When we first started casting people, you immediately knew whether or not someone was in it for the right reasons. And the charitable piece, I think that was a really unique piece of the format. They didn’t have to stay there. They could leave at any moment, but they were all there fighting, sleeping in the rain, not eating much, trying to win as much money as they could for the charity.”

Indeed, the elements hit the cast hard from the very beginning. Just as shooting got underway, an unexpected massive rainstorm rolled in. “The first night that they slept in the jungle, it poured the entire night,” Goldman says. “That was a real test, and we were waiting for the emergency walkie call of like, ‘we can’t do this anymore.’ Miraculously, that call never came.”

“Beyond the Edge” is not “Celebrity Survivor,” and that’s something CBS and Renegade want to make very clear. The show has some of the hallmarks of “Survivor,” including the tropical beach, physical challenges and the same broadcast network home. But in “Beyond the Edge,” there’s no elimination — the celebrities only leave when they physically reach their breaking point (and a few do ultimately drop out) — and episodes end with a bit of a therapy session, led by host Mauro Ranallo (from Showtime Sports), as the stars discuss the challenge they just accomplished.

Specifically how it works, every day that a celebrity is on the show, they make $2000 for their charity. Beyond that, the bulk of the additional money comes via adventure challenges. New teams are picked in every episode, as they compete in a challenge that comes in three different stages. The first team that completes it wins a pot of money, which grows every episode. “It’s not enough just to stay out there,” Goldman says. “You obviously want to compete and be competitive and win these challenges. Eventually when you get to the finale, the two celebrities that have earned the most money face off against each other for the final pot. The winner is the one who banks the most cash along the long way.”

Goldman also dismisses comparisons with “I’m a Celebrity, Get Me Out of Here,” a popular international format that failed in two tries in the U.S., and was much more about stars conspiring against each other in the wild.

“We know people love celebrity shows,” Goldman says. “We’ve seen celebrities dance, we’ve seen celebrities work. You’ve never really seen celebrities have to survive, especially in an element where you’ve got the most lethal snake in the world, you’ve got crocodiles, you’ve got bats. These celebrities are incredibly emotionally vulnerable in a way that you’ve never seen them before. They have breakthrough moments out there and ultimately come together to do something that’s extremely positive and uplifting.”