Here are some ideas https://www.hometalk.com/search/posts?filter=Curtains%20in%20Decorate
In our RV, it came with a valance and horizontal mini blinds. Not a fan, as we have traveling pets. I just replaced by making curtains. Here are more ideas.
Bonnie, are you wanting to clean them? Cover them with cloth? Make them insulated? If ou make our need more clear it would make it easier to answer your question.
If you're going to be doing winter/cold weather camping, most make window covers out of reflectix mylar insulation and cover them with fabric to reduce heat loss. https://www.youtube.com/watch?v=PS44T9LPnGg other fasteners you can use are snaps, velcro or fit into the window edging tightly