If you are using All Trumps, the rated absorption for that flour is around 63%. So, you should be able to increase the hydration a few percent without a problem. As tcarlysle noted, that should result in increased extensibility. However, some members have reported, at http://www.pizzamaking.com/forum/index.php/topic,10622.msg94384.html#msg94384
, that they have found the AT flour to produce a stickier dough than other high-gluten flours. Consequently, you may need to fine tune the amount of water to use with that flour.
There are several ways a dough can become overly elastic. It can happen if the dough is underkneaded or overkneaded. It can happen if the dough is underhydrated. It can happen if the dough is underfermented, or it is worked while cold or if it is re-worked, re-kneaded or re-balled shortly before using to form skins. Adding more oil, e.g., up to 3% for a NY style dough, will improve extensibility (reduce elasticity). Adding sugar will not have a similar effect.
What you might want to try before making changes to your dough formulation is to make a smaller batch of dough than the eight dough ball batch you have been making. It is possible that hand kneading such a large batch using All Trumps is not producing a sufficiently hydrated dough with optimum gluten development, which is a factor in determining the ultimate extensibility or elasticity of the dough. Whether you heed this recommendation or not, you might also sift the flour and use an autolyse or similar rest period. Doughs using high-gluten flour are harder to hand knead than doughs made with weaker flours, so when I have hand kneaded high-gluten doughs my practice has been to use a combination of sifted flour (to improve hydration), high hydration, and an autolyse or similar rest period. In my case, I was making only single dough balls of around 20-30 ounces or so. It would be considerably harder to hand knead an 8 dough ball batch. Making a single dough ball should help rule out hand kneading issues if you get the desired degree of extensibility.