Lost space from negative pressure

Some tents have added supports to help prevent this. One other option is using walls that are not flexible. Or backing them with a thick sheet of plastic. its a lot of extra work though. The tent I use has a mid bar support to prevent massive suck in, but it still sucks in a bit. You could also try increasing your passive air intake by introducing more ports if you have the option. The more air coming in the less it will be under negative pressure and the less sucking in it will do. OR reverse the air flow and have it under positive pressure and blow it up like a balloon. also works. Good Luck!

I use telescopic rods that I put between tent's poles, works great and doesn't cost much. Good luck, growmie! 😽