Is there a way to have the same MAC address on both the pNic and the vNic?
I'm afraid no. The ESXi Management and any VM need their own MAC addresses in order to work.
I'm not sure I understand the physical setup correctly (separate router!?). However, what might be possible, is to run a virtual router on the ESXi host, have the VM's on a private network behind this router and connect to them using port forwarding on the virtual router.
André