For future attempts, a layer of acrylic matte medium would work well as a primer layer. It dries clear and you can pmuch do as you like. Edit: Just realized that saying matte medium implies something like Liquitex or whatever in those $16 bottles, I meant the matte ModPodge you get in little tubes for like $1.50. Cheap easy and everywhere.
Maybe some watercolor ground as a primer? I have been thinking about getting some to experiment with. Good job despite all your troubles on this surface.
