Drying on a paper box at balcony?

Any DIY trick to check humidity?

it should work, just make sure to open the box daily to check for any problems. since it may get windy, i would put some bricks on the bottom of the box, all you need is on good gust then your plant will be flying in the air. you can always use a card board box with hole punched in. put small holes in the box using a pencil for air.

As long as it doesn't get too hot and you can keep the humidity in check, you'll be fine. 80°F maximum and between 45-55%RH ideally.