BRB's in melamine enclosures?

[GYMRAT2B]

I'm interested in getting a 1.2 trio of BRB's but I just had new 4-cage tower melamine cage made. The cage is great but expensive. I want to be able to keep BRB's but I was told that the humidity that they need would warp the wood in the melamine and shorten the cage's lifespan. I'm sure I can use aquarium sealant but that would defeat the purpose of the moveable panels I had designed to change the size of the enclosures on each shelf. I thought about just putting a rubbermade box in an enclosure, fill it with wet moss and cut a hole in the lid. Will this do for BRB sub-adults? And when they do become adults, how much humidity do they need?

Thanks