I have a glass tank. 30x12x12. I use apsen substrate and have a foil wrapped lid top. I have 3 sides insulated with foil tape + styrofoam, and a CHE.

My bp just finished his second shed today and it was all in full pieces. I just spray hot water when i see signs that he is about to shed.

There are different techniques to keep humidity up, but this is what's working for me.

As for plastic containers go, i would imagine it would hold humidity better because its plastic vs glass.