Maybe a specific, additional one for it. But probably many are also going on the expedition and taking part or even helping out in other ways. So if there's to be a decal for the expedition, I think it should be a more general thing. Maybe for signing up in the fleet roster and making it out to Beagle Point? I seem to recall that's how the previous one worked, though I didn't go on that expedition – my ship of choice couldn't make it back then anyway.
But sure, an addition one would of course be cool. Not sure how generous and proactive Frontier are with this sort of thing though.