You can add this script in your custom page node to hide the header and footer

Run on Enter

<script>
        document.getElementById("header-editor-preview").style.display = "none";
        document.getElementById("footer-editor-preview").style.display = "none";
        document.querySelector(".header-container").style.display = "none";
        document.querySelector(".footer-container").style.display = "none";
</script>

Run on Exit

<script>
  setTimeout(() => {
    document.getElementById("header-editor-preview").style.display = "block";
    document.getElementById("footer-editor-preview").style.display = "block";
    document.querySelector(".header-container").style.display = "block";
    document.querySelector(".footer-container").style.display = "block";
  }, 500);
</script>

See example decision tree here: