20g Upgrade Plans

[SwimminSteve]

Hi all,

I recently bought a 20g long tank at Petco's dollar-per-gallons sale (it's like Christmas for me). Maasai is probably about 4.5-5 inches SVL now and I think he'd appreciate more space, specifically more water. Divided half land/half water tanks are gorgeous, but I'm not looking to make any permanent modifications to the tank right now. I would prefer to find a large container that would sit on one end of the tank and would basically be a removable tank. I'd like to find something that fits snugly and about 4-5 inches deep. I would then use a Tetra 40i internal filter (from an old tank), I'd still do a partial weekly water change.

Right now my water dish is a small square pyrex dish. He can submerge, but I know he wants to be able to hide better. I like my pyrex, but I would rather move to something plastic (less heavy/breakable). However, I'm concerned about unsafe plastic. I've been looking at storage bins and even cat litter boxes, but I worry about chemicals leaching into the water over time. Is that a legitimate concern?
Has anyone done this type of set up?

My goal is to provide for his desire to burrow in substrate and also to submerge under water when startled, of course I want it to practical to clean, but I'm really hoping I can simulate a more natural GABF habitat- like a flooded wetland. Has anyone ever tried different substrates like mud or sand before? I like that look better.

Thanks for any tips!

[SwimminSteve]

OR I could use the plastic container for the land area and just put the water straight into the tank. Too many possibilities! Ugh!