Thanks for posting this. I like the idea a lot. A couple of points...
1) I would prefer using a bracket that connects via rigging points like the M10s on my K10s. This would be to avoid the unlikely, but possible situation where the tent bounces around causing the speaker to bounce off the pole mounting (also a possibility with tripods, but probably closer to the ground) and instead provide a mount that doesn't rely on gravity.
2) If you're able to suggest layout, having a tent with a stage under it at one end, and the audience in the middle and at the other end, running longways, you can ensure the stage is behind the speakers. In the OP picture, the seats would orient facing one end instead of one side. Obviously not an option here since half the audience is not under the tent. However, using that pic, there are 6 poles per side. The speakers could be mounted in the #2 spot and the stage between #1 and #2, audience between #2 and #6.