Lia that is a super cool outdoor enclosure! I dont think my FBTs would fair as nicely as yours if I put them outside.....
Not sure if you want a "build" project or not but if you do, I would suggest a false bottom set up for this tank. Your plants will be happier and it will be a lot less hassle in the end. The cost is more and the build is a bit more complicated if you choose this style however its really not that hard and the realism can be superb. I have done the leaky plexiglass thing a couple of times and will never deal with that again. JMHO.
You can get super creative with the initial, egg crate base and have a great, naturalistic shoreline. A basic, great stuff background wouldnt cost much and you could silicone/coco fiber the whole BG to encourage moss growth. Probably all for under $75 at HD.
The 40B is such a perfect tank for a group of FBTs. If you want aquatic plants, the shoreline idea would be great. Riparium plants at the edge and low light, easy aquatics like anubias sp. or those small crypt packages from PS would be my choice. FBTs will monster truck your plants a bit so try the more hardy sp.
Filtration is a must with FBT. They will access both terrestrial and aquatic realms at will, carrying with them all kinds of debris. A nice canister filter like an Eheim 2213/7 would give you some gorgeous clean water!
Bill did a great job on his pauld shoreline in this tank:
Madagascar inspired Mantella tank
A poly build would work as well if you wanted:
Newt Tank Build
Hope this helps, and best of luck with your build! keep us all posted on its progress!