Just a few questions based on the 4 foot height.....How will the terrarium be accessed for maintenance and feeding? Considering you would need front opening enclosure due to the narrow width and taller height, you need to consider access and the closure of the access pretty closely if you intend to have a tropical setup. The front access will need to seal really well if you are going to run misters. Also, with a mister you may need to consider a possible subdrain....water in = water out...or you could end up with a flooded substrate.

I would search a few setups for dart frogs for inspiration. For tropical display vivarium, those guys have a lot of the issues worked out.