WBBB top cover?

[tritan]

I was out last week and used mine. The overnight low was 26* and no condensation inside. I did have ice on the outside of my tarp though. I have had condensation with temps in that range before, but I was pleasantly surprised when I got up with none last week.
I'm hoping it will be warmer tomorrow night and I can leave the BBO in my pack...

I don't have an underquilt yet would this be a cheaper way to hold heat in?