secure boost::beast::websocket server with SSLKEYLOGFILE support

I have a secure websocket server written with Boost Beast using Boost-asio. A significant portion of the connection code is documented here. The server uses RSA keys for TLS encryption. I would like to use tcpdump to capture the websocket traffic coming in/out of the server and use Wireshark to view the decrypted content.

On the surface, this should be easily doable. Wireshark documentation says how to do that via the RSA private key. The problem is that the documentation also explicitly says that it does not work for TLSv1.3, which is now my clients connect. Since, I do not support PSK auth, that just leaves me with SSLKEYLOGFILE style key log file using per-session secrets. The problem is that boost does not seem to honor the SSLKEYLOGFILE environment variable.

This seems to be confirmed in this unanswered question. While that question suggests that it could be doable, I do not understand how. Any help would be appreciated!