The existing valance was actually stapled onto a piece of thin plywood. As you can see in the picture, there was stitching to create texture. So, we decided the easiest thing would be to cover the existing valance. We bought long thermal blackout curtains from the Dollar store. Then, cut the curtains to fit the sizes we needed.
Items you would need for covering the valance:
Staple gun & staples
3M Spray Adhesive
The fabric needs to wrap around the valance piece. We attached the fabric to the existing valance piece with staples on the back side & used spray adhesive on the front side. On our valances, there is a piece of wood that attaches to the underside of the cabinet in the RV as well as the fabric part of the valance as you can see in this picture...
This piece was attached with finish screws. So, after the valance was recovered, we reattached it using finish screws
We used the existing curtains to determine the sizes for the new curtains. The new curtains we bought had the seam already sewn in for a curtain rod on the one end, so we sewed a new seam on the other end/sides, as required.