Good advice, thank you this could be a problem haha. I have tried feeding Prickly Pear and they eat it. The two Desert Tortoises I have I don't think ever turned anything down that I put on their feeding rocks. I also keep some fresh Timothy Hay laying in a pile (not the best grass but my daughter insisted her rabbits only can have this so we buy a bale at a time) and munch on it stem to flower. About a month ago I put a cuttlefish fish bone on each of their feeding rocks (i never offered it before unfortunately)and they are even eating those a little at a time now. They are walking walking vacuums. So easy to feed.I live in Phoenix and my native Desert Tortoise has access to all of the Prickly Pear pads that she could possibly eat. That being said, she refuses to eat them. I "dethorn" them as much as possible, I cut them up as well as offer whole pads; and the same goes with the fruits that are currently ripe and sweet. Her response: Total rejection!
So, before you plant you might do a test run to see how enthusiastic your tort is about eating. If she is like mine, don't bother. If she likes them, start small and see how it goes.