So in a good few places in the UK prime mover callsigns are very interesting. They tend to switch callsigns depending on the pod being carried. Now I think this would be pretty interesting but quite a challenge to implement. So maybe when you purchase your prime mover you're able to set the callsign for the prime mover (Ex: N01T1). When you buy a pod you can also set the callsign for the pod (Ex: N01H1 (EnvPU pod)). When you set your prime mover to pick up the pod, it adopts the pods callsign.
Pretty interesting idea in my opinion, let me know what you think.