I'd say stick with the same basic setup you have, with a few more hides, and get either a bigger aquarium (40 gallon breeder or larger), or build yourself a new cage just by looking at what others have built, researching the caging forum, and finding the best ways for doors, vents, heating, etc. through all of that.
Either that or you can go with a company like custom cages or boaphile, but I personally would build one (or try to) if that's the style caging you want...meaning not an aquarium.
By the way, I like your setup...very nice looking, and the snake looks even better.