Fast n Final lightweight is still white. I just bought some because I’m painting the house. I get it at Lowes. Started using it when Greg Leohr recommended it.
To avoid air bubbles with low density EPS ( I used to use mostly 1.5lb) make sure you glass on falling temps. I would try to glass late afternoon/early evening. Or you could preheat the blank by leaving it inside a closed up car on a hot day. Then taking it out and glassing it as it cools.