How are network stack modifications tested?

I have the task to develop a modification (using eBPF) of the TCP stack of the Linux kernel, and I need to test its interoperability with non-modified kernels. Specifically, the eBPF program should be able to inspect some TCP header information, and possible retransmit the packet to a different IP. How are such modifications usually tested? So far I've considered: 1. Using one VM for the modified version, and one VM for the unmodified, and then using mininet to connect them and create various testing scenarios. 2. Using containernet (instead of mininet) to load containers with the eBPF program, but attempt to create a runtime flag in the eBPF program so that it will only act in one of the containers. 3. Use separate hardware, and create a physical testbed (which I find undesirable). How do those of you that work on such projects usually test your changes?