Sadly, I have all of the elements that Skylsdale despises in my enclosure.
This currently houses a group of Mountain Horned Dragons. Originally, it housed my six-year-old water dragon, who unfortunately passed away about 2 years ago.
I agree, to a point. Often times they do look cheesy, but in my opinion, and experience, function outweighs aesthetics in terms of maintaining an animal occupant larger than a day gecko. All natural vivaria are stunning - but a grown water dragon would trash it inside of a week. When I obtained my dragon as a hatchling, I gave an all natural setup a shot - live plants and all. The juvenile dragons claws made quick work of the leaves and stems, and those that it couldn't shred, it instead uprooted. In short, it was frustrating. I won't say it's impossible, but will likely require a good deal more research and work on your part to meld thriving live plants in a water dragon enclosure. As for the plastic pond, I say go for it. Sounds like a great idea. Use an adequate heater and pump and you could indeed have both a supremely functional, and visually beautiful enclosure.
My enclosure for a single dragon was 5'H, 4'W, and 2'D. There are others that have created very
large enclosures and have incorporated live plants successfully. Check out George Buce's
water dragon setup, or JWorlds Enclosures
(These are not live plants, but absolutely stunning nonetheless. Best of luck with your dragon, they are wonderful animals.