Good for you for wanting to change the look of your trailer interior with DIY curtains! You have already received some great advice; cut fabric 1 1/2 to 2 times the width, line with muslin or white fabric, match the washing instructions for both the interior and lining fabrics. I like to make curtain panels while keeping the original off-white fabric curtains that came with the Scamp
.Novelty fabric patterns can be overwhelming if used all around a small space.
Be sure to pre-wash all the fabrics so they don't shrink in the future. I created tie-backs that fasten to the rat fur walls with the hook side of hook and loop (Velcro) fabric. I made "shades" (of Ron-Loc, a block out material) that hand roll on a dowel placed on top of the curtain rod holders. See photos.
fabric is the same in both photos. They just photographed differently. The two photos show different fabric designs. My Southwest motif is accessorized with matching pillows, fleece throw blankets and stuffed animals.
Have fun with glamping your rig!