putting arrows on 3d stroke

Good Evening Everyone,

I am doing a simple route map, showing the route a traveller is taking across the world.. I have a flat map and I am using 3dstroke to animate the path from A to B.. easy...

However the client has now piped up, and decided they want an arrow on the front of the line, that animates with it.

Can anyone think of a clever way. I'm thinking the best way is to use the path as keyframes, and put a triangle on the line and try and match the timings..

Can anyone think of a clever way to get round this ??

I am thinking there might be a way to use the key frames of the 3d stroke to move the triangle along the path.

thanks for any help

kind regards

Alex