Sturry Rail Box and Light map woes

I have an interview tomorrow with Railworks (Rail Simulator) for a Junior CG Artist job. So I'm trying to get some practice in (and I'm going to take this along with me). Here's a render of the model.

This was my first attempt at baking light maps, it came out super low res, but it has charm I think.

This is how the Light maps come out. It ruins your UV's, not convinced this is the right approach!