How to animate object shape and import to Unity (FBX)

Hi guys, I've got an aircraft model that I've been working on for a project for a while now that has lots of keyframed animations for landing gear animating, flaps moving etc. What has me stumped right now is how to animate the engine exhaust vanes, which on virtually all fighter jet aircraft change shape depending on the amount of thrust the engine is putting out.

Example - when on afterburner, the engine vanes usually open all the way to allow maximum thrust to escape, while when at lower thrust, the engine vanes will close to channel the thrust out a smaller hole.

Now, due to low-poly requirements, my engine vanes are currently a single object. In 3ds Max, I've keyframed the vertexes on the vanes to animate them opening and closing nicely, however I now realise that Unity doesn't support vertex animation or even point cache files, so I'm wondering how else to go about this?

I know there are a couple of scripts/plugins for Unity that will allow it to import vertex animation, but I'm just wondering how else you'd go about animating this sort of thing without having to go to 3rd party products.

Thanks in advance guys.

Rant - To be honest, it's absolutely astounding to me that Unity still does not support such a fundamental feature that developers have been calling for for literally years. It's frustrating to see them getting caught up on niche - ie, limited to specific usage cases - features like mechanim when they've still got a hell of a lot of basic functionality to get right, like this, the implementation of path following animation, resolution of the co-ordinate incompatibility handedness issue between 3d modelling apps and unity etc.