Got exactly the same problem.
Found your inputs useful.
Modified the css to add the pointer.
Finally changed the header.php. Had to get rid of the blog description and replace it by a space.
Code looks like this:
<div id=”page”>
<div id=”header” onclick=”location.href=’https://www.cooperatique.com/'”>
<div id=”headerimg”>
<div class=”description”> </div>
</div>
</div>
<hr />
I know my div look strange and don’t ask me why there is <hr /> in the end.
But at least it works enough for me, till I install the new WP version.