if its just for transport and you don't really care what it looks like it would not be all that hard to mask the area around the window with tape/foil and then lay down a layer of fiberglass resin over some fleece. IF you do care what it looks like then just build it up a little and then sand and paint.
I don't have a pic, never done it myself but I have done fiberglass and it could be done. Like I said you would have to mask the area around the window and then put down a layer of fiberglass resin on some fleece and then shape it inHello TTOCS, I do not have Instagram can you share a pic of what you are talking about? Thanks Randy