Hello Tim
You use the Pereskopsis?
I grafted seedlings on that and met spines, it is affordable to me. And my
friends are get used to that spine, but he not use the Opuntia humifusa.
Maybe this could be a solution, use the fire to burn the spine.
I put a Zipper with fire close to my TH, and its spine burned away,
it not hurt the body at all. It just takes less that 1 Seconds.