How do I identify which lightmap is used where?

So I upgraded my project to unity 5 and am having some issues with baked lightmaps - compressing them gives serious banding and overriding the max size gives edge artifacts, regardless of padding.

The best trade off I can think of is to compress and/or override the lightmaps my player doesn't get close to - is there a way I can identify where a lightmap is used? I thought right clicking>find references in scene would do it but apparently not.

Note: these are fresh bakes from v5 and I want to reduce the file size of my project - at the minute the lightmaps take up more than 50% of the filesize (total 111mb), whereas on v4.6 I had a decent quality bake and kept my entire project just under 50mb

Thanks

 

Thanks.