Should I add rain to my snake's terrarium?

Technically this is my Mum's snake. She is a Boa Constrictor Imperator. I know All Boa Constrictors originate in tropical environments and like humidity. So, what I was wondering- can I recreate a rainforest and add a mister (mist sprayer) to her cage, with a timer to briefly pray around her terrarium once a day (or week)? And if so, what kind of substrate can I use to absorb some of that excess water