Night textures blurry, day stay sharp?

I've been wrestling with this one for days now and can't find a solution. I've repainted an aircraft (Aerosim 787) using their paint kit psd's. The native size is 1024x, but I've increased the size to 2048x prior to painting.

The larger textures look perfect during the day time, sharp lines, smooth curves, rivets, etc. However, at night, the night and _LM textures look like they're half the resolution, smeared all around the aircraft.

This occurs if I use anything other than dds 888 32, which unfortunately results in 16mb textures. If I save as dxt5 extended, or dds dxt5 the blurring at night reoccurs.

Question- why would the night textures be the only ones affected? The dds dxt5 textures look perfect in the daylight?

Any other way to reduce these file sizes without this ridiculous night quality issue? B)