The answer is no! Even if you decide to do the Overland Track off-season, when the permit is free, you still need to hold a current national park pass. What if you want to experience the Overland Track during the summer season, but you can't afford it? Interestingly enough, you can get on the Overland Track without paying the booking fee, and do a day or two-day hike instead. Check out the Overland Track alternatives.
It's always about finding balance between keeping your pack weight low, and having all necessary gear with you. Honestly speaking, I think I did a great job packing for the Western Arthurs Traverse. In fact, I wouldn't really change much if I had an opportunity to do so. I wasn't lacking any gear, and most of the things I brought on this hike were used at least once. Here's my Western Arthurs Traverse gear list. Enjoy reading!