For this size of a tank, I personally would go the terrarium route. Cover the crack, build it up, add a water feature and enjoy something that IMO is far more enjoyable than a simple cage with a solitary large snake. Now, there are some very interesting snakes, (Im hoping to add a pair of a very interesting sp soon) but that large of an enclosure, id have to go terrarium. In my collection it would likly go twords vine snake, green snake, ring neck or some other similar small sp snake. But then again, I like snakes that stay smaller and would truly be able to enjoy an elegant terrarium. For lizards, id go maybe a bunch of salamanders, geckos, anoles etc. again small but can enjoy elegant enclosures. Remember, unless you truly keep your cage bare, you will not always be seeing your animal which is why I am so decoration heavy. Heck look at my caiman den. As she grows, she will destroy many of the plants, but for now its beautiful. You also lessen the risk/impact of empty cage syndrom with more animaks per cage and better decorated.
All this goes out the window if you want something to hold.