So, my suggestion is as the title says, pretty self explanatory. Unfortunately I have zero coding expirience so I can't do it myself.
So my idea of how it would work would be pretty much like swapping textures work, you would first select the model you would like to swap, then the model you would like to swap to and click "swap models on ADT" button.
I suppose swapping models per chunks wouldnt work well as many models take more space than a single chunk.