Are you going to have this professionally welded? I would not recommend you welding this yourself unless that is what you do for a living. Most cage failures are from poor welds. What do you want protecting you, your safety, and well being?
For the price of getting someone to weld the kit of tubes that you bring them from Rhodes and then fiddle with things that don't fit right or that you want customized, plus the cost of the Rhodes kit shipped to you, you may be at the same cost of having a cage builder do the whole thing.