Clickable product image with hover effect

You can use some Javascript to trigger the click. For example:

$('.product-thumb').click(function(event) {
    var product_link = $(this).find('product-thumb-primary a');

    // Don't trigger a click on the existing link
    if(!event.target.href && product_link.length) {
        document.location.href = product_link.attr('href');
    }
});

Un-tested but that’s the basic logic.