What sort of adversary are we talking about here?

If it's the government, and it can coerce ISPs, then the short answer is it's impossible. (That is unless you control every meter of wire and every single piece of networking equipment between you and your peer.)

If you bypass IP packet censorship by using an alternative to IP, they will just move the censorship one layer down, intercept the "bare wire" data and filter out all signals that don't look like IP packets.

There would be no way around it other than literally building a separate physical network (mesh WiFi, LoRaWAN, private satellites etc.).

The way we deal with censorship on the Internet is on higher layers - encryption provides us with means to obscure the content as well as ensure no tampering. But that assumes the lower layers are free from obstruction.