The title says it all. Which would trigger first if they were both used? Both cards say, "When you reveal a green maneuver..." Could you barrel roll with BB-8 because you chose a green maneuver and then choose a different maneuver with SoT? I'm thinking not, but what say you?

Yes. They trigger at the same time, so you can pick the order of resolution.

It's rather devious, actually. Barrel roll, then adjust your maneuver to give you the best position. The problem is that, due to the stress from SoT, you're only doing it every other turn.

Thanks!

Strictly-speaking, you /should/ fulfill the BB-8 condition by revealing a green.

Here's a fun one: if you somehow had a way to get PtL+SoT, you could reveal a green, perform a barrel roll, PtL into an action, SoT to red, end up with 2 stress, and your opponent wouldn't get to pick your move because you didn't reveal a red maneuver while stressed, you just changed the faceup maneuver.