Ok.....your metal hooks off your light are connected to string right? The string is connected to the top of your pcv tubing......is that correct?

If so.....get some strong wire and loop it around your pcv tubing where the string normally is. Then remove the string and hang the light directly from the metal hooks to your loooped pvc wire. You should gain two feet. It most likely will be enough......especially if you can lst a little.