Backcountry Navigator, can you only download max zoom?

[1leglance]

I have been using Backcountry Navigator on my Android head unit in my van. It isn't as good as OziExplorer was on a netbook but for now it works.
However when I want to download new maps it frustrates me that I have to download all these different zoom levels when all I really want is max zoom of 15.
Anyone know how to only download that layer and thus save space and time?
Thanks