Making a lightweight crestie viv

I've been thinking of getting a crested gecko but I've been wanting to explore options for a viv that won't weigh too much to move around (that may seem like an odd requirement but I'm an apartment dweller and it's always a pain with my snake tanks). I'd like something in the 18x18x24 kind of sizing. I've seen screen vivs in that size but I'd assume that would be a mess for keeping humidity up. Any alternative suggestions or maybe modifications to screen vivs people have tried? I was considering maybe getting a screen one, setting one of those deocrative textured foam backs up on the back and maybe figuring out something to do with the sides but anything less heavy is a boon.