There's also the not-maintained (because outdoors and no longer used) Mississippi River Basin model, built near the site of a WW2 POW camp in Mississippi. Italian and German POWs provided the initial labor for site preparation.

It covers 200 acres (~80 ha), vs 1.5 acres for the Bay model.

https://en.wikipedia.org/wiki/Mississippi_River_Basin_Model

If you have an interest in going (I've never been despite growing up in the area and having family there still), I would advise waiting for cold weather - it is perfect snake habitat, and water moccasins are both venomous and relatively aggressive.