I had very bad experience using plastic wads over BP in 12 ga. Hulls!
I wound up scrubbing out plastic sheets with BP fouling. It might depend on wad brand but my barrel was lined with plastic!
If you use nitro and hard card wad column under a shotcup with cushion leg and seal cut off it might not be an issue. Using a lubed felt wad under the shotcup might be a good idea too.
Maybe others have had success but my experience using cushion leg plastic wads over BP was very bad!
YMMV
Longbow