Dude, I see huge huge headaches in your future, especially at the temples. I am not sure if you are aware of it, but those bad boys will become the thickness of where the hair meets the scalp, so if you have a 4 inch section at the scalp of all the hair joined together, then you will have a 4 inch mature dread. Can you imagine the weight of them as they grow? Can you imagine how heavy it will pull on the scalp, especially when they are wet? Look at the size of the scalp area at your temples, headaches will happen for sure! Besides tension on the scalp causing headaches, it will also start to pull out hairs with the weight. Those just might take about 48 hours to dry when mature, they will be so fat, they will also be prone to mold, so you would have to be so careful that they completely dry out in between getting wet, that would be so hard to do when it rains out.
Okay, so what can be your future problems again, scalp tension, heaviness, mold, headaches, hard to sleep with them, did I say mold???
As cool as they would look, the problems over ride the coolness. If you want fat congos, consider dividing those, anything over an inch is considered congos. Once they mature and you really find out the problems you will have, it will be harder to separate them, you would have to slice them down the entire length with a blade.
Your hair, your dreads, your decision, but I feel I must let you know of the future complications you may have.
Peace