Hi Eli, A large cage is basically the same as a small cage. You establish a base heat. Say, 75F, this could be done in many ways. With a large cage, some sort of heater. What works best in your area and with your services(propane, gas, electric, etc) You know, like heating a room.
Then use banks of lites for a hot spot. I have found its far less expensive to use a number of smaller wattages, then a few higher wattages.
I split a log and mount the lite bases to the flat side. This way, the monitors can use the top to lay on, and bask under lites.
With a cage the size your thinking about, I would use at least two of these areas. Remember, the base heat is done with some sort of ambiet heating, as mentioned already.
The type of construction would be based on the actual site and area your living in, so I cannot go into depth here.
I feel the ability to change the cage is very important. Most folks around here think I know it all, but actually I plan on not knowing anything and keeping flexible. Its more important to be able to execute your decisions, then knowing somthing.
So, make large doors, or removable sections, so you can move large objects in and out. Or competely change the cage, EASILY.
Next, make it easy to move food in, and feces out. This is very important. I find, the monitors closest to the kitchen are the most productive. Which means, the monitors the farthest from the food storage area are the least successful.
This goes for water too, make it easy. If you make it difficult, your monitors will suffer. Make the dirty water easy to get out. This is very important.
As you know, a lot of people get all concerned about species and aboreal and this and that. As you can see, I do not feel any of that is important. In fact, its meaningless. What is meaningful is having a cage that functions. If the cage functions, you can change it back and forth, it to cover all those things. And things you don't know about, yet. Its these things that will get you.
With crocs, I would make a cage that can isolate the animals. A larger comunity section, and a couple of smaller sections to house individuals that for some reason may need to be seperated from the main group/pair. So, what do you think? Cheers