I've been growing my nepenthes in a Secret Jardin grow tent (4'x4'x8') for about a year, and I have no complaints except that it clearly wasn't designed for high-humidity growing. I have a sheet of plastic inside it on the bottom to hold most of the condensation that rolls down, but of course this won't stop all of it. The tent leaks slowly but steadily onto the floor below it (which is why it's sitting on another sheet of plastic -- I just towel up the puddle once a week). The metal frame inside is also coated in rust.
I suspect I'll have this problem with any tent I buy, but maybe you'll surprise me. Does anyone know of a tent designed to be drenched all day? I'm looking to get a bigger one and I'm tired of leaks. I might actually install misters if I knew the water would stay put. I'm tempted to just make one out of PVC pipe and thick plastic, but I know I'd miss the zippers.