My cage is that size for my Jax and fully screen, so I understand the humidity concerns. The plants help a lot. Honestly, I run my mister for longer sessions to compensate and don't worry about ambient humidity except in winter. My lights run 7:00a to 7:00p.
8:00a 15 mins
10:30a 5 mins
1:00p 5 mins
3:30 15 mins
6:00 5 mins
In the winter, I run a small cool mist humidifier directed into the cage. It's a lot of water, about a gallon a day, but it works well.
I also provide my Jax with a dripper for a few hours most days. Sometimes he likes to sit under the drips. Seems to make him happy.