Untrusted distributed nodes?

[dom]

Nope, see also: https://github.com/erlang/otp/wiki/FAQ%3A-What-kind-of-patches-will-be-approved%3F#can-i-write-a-patch-to-increase-the-security-of-the-erlang-distribution

You can implement a custom protocol pretty easily with term_to_binary and the {:packet, n} options to gen_tcp though, if your use case is something like task dispatching.