This is the only description in the book about them:
"There was a blow on the door that made it quiver; and then it began to grind slowly open, driving back the wedges. A huge arm and shoulder, with a dark skin of greenish scales, was thrust through the widening gap. Then a great, flat, toeless foot was forced through below. There was a dead silence outside."
I really love your interpretation of Tolkien's cave troll, especially since he gave you so little to work with. What brings this piece alive for me is the way that this guy attached the weapons of his slain enemies to his club, both making him more intimidating and more actually dangerous at the same time! Also, the Dwarven skulls and axes that are a part of his clothing--a nice touch. I think the entire Fellowship would be hard pressed to stop this guy!