How do I redo valances and curtains in an old RV?

I answered your seat questions in the other post.

You can recover or even paint the valances. The curtains are a matter of having access to a sewing machine.

I would rip out the carpet and replace it with carpet tiles that can be removed and washed for spills.

Hi Kim, it's easy to paint the valence if they are the metal or plastic ones, the other thing you can do is buy new vinyl blinds, cut to size at any hardware store like lowes or home depot, or go less expensive and buy from walmart, and shorten them yourself and leave a few extra slats in each in case of accidents, I did our trailer getting them cut to width at home depot for about $175, they come with their own slat valence, looks more modern. for the carpet, you could try to dye it, but I would just lay new mats over top if you don't want to spend a ton

If you don't sew, you could use a product like Stitch Witchery to hem them. Use fabric that is easy to clean.

If it was me I would rip out the old carpet and put in vinyl. Add throw rugs but keep it so it is easy to clean and the throw rugs can put in the washing machine when needed.

Why not go with something different for the windows? Depending on the dimensions you could do mini blinds or roman shades.