Right now its an open top set up. The long term plan is a canopy on top that will give it a bit more head room. At that point I'll probably put in a small arboreal snake, maybe a Smooth Green Snake or two.
The problem with Greens is that they're so cheap that nobody takes the time and effort to clean them up and out the way any wc snake should be. And since they're so cheap few people bother breeding them, so wc is usually the only option. Wcs willl be all over kingsnake.com in a month or two.
My understanding is (beyond the parasite issue) that part of the problem is that they are a rather timid/nervous/flighty snake that is stressed out quite easily. Stress weakens their immune system and combined with a likely parasite load tends to do them in. I don't know of anyone who has tried them in a densely planted (or furnished heavily with fake plants) tank. (Though I would think there would be folks out there who have done so.) A tank with plenty of cover might help them feel more secure.
I saw a baby at a herp show last year. Almost picked it up. But the girl at the sales table had no idea if it was captive bred or wild caught or even if it had eaten for them.
I'm planning on redoing things a bit to lower the water level and make the land area a bit smaller. Then I'll add a Vireya, build the canopy and get some snakes.