They could try a different port - some systems won't bother. They might also use TLS with null cipher. That should be not-so-intensive, even on a tiny processo

They could try a different port - some systems won't bother. They might also use TLS with null cipher. That should be not-so-intensive, even on a tiny processor. And it could be enough to defeat some packet-modifiers (they may notice it's TLS and not analyze), while maintaining HTTPS compatibility.