I'm not sure I completely have got my head around the idea. You have one every x many chunks, it acts like the current stations, when a cart comes in any one there is sent off back in the direction of the one that came in and the one that comes in carries on straight through. Hmm, sounds tricky
I'm wondering if the problem is not that the carts enter unloaded chunks but more that every so often any entities in unloaded chunks are cleared out. Which would mean that no matter how you do it they would have to be stored somewhere (chest or dispenser really).
Please don't use the delete button, think of the children.