So, I have a simple SVG group:

<g id="interceptor">
    <ellipse cx="0" cy="15" rx="6" ry="14" fill="url(#gradient)"/>
    <polygon points="0,-20 7,10 0,0 -7,10" fill="blue"/>
    <polygon points="0,-20 7,10 0,0" fill="darkblue"/>
</g>

Which I then use like this:

<g class="ship" id="ship3" transform="rotate(-180,480,24) translate(480,24)">
   <use xlink:href="#interceptor"/>
</g>

Now, what I would like to do is to add a stroke around the first polygon from the group when the whole group is clicked, but I don't know how to access contents of the interceptor group via jQuery. I was thinking about something like this, but contents() returns nothing:

$(".ship").click(function() {
    $(this).find("use").contents().find("polygon").first().attr({"stroke-width":1, stroke:"white"});
});

I can, of course, add a stroke around the entire ".ship" and it works, but it's not what I want because this creates strokes between polygons in the group. Additionally, there can be a number of separate objects that use the #interceptor group, and only the one that is actually clicked should get the stroke. Is that doable?