That is a beautiful panel and your accessory fabrics are too. I just purchased a Santa door panel and it was uneven too. I threw it in the washer under rinse cycle only, hand wash. After it came out of the washer, while still wet, I sprayed Magic Sizing on it and ironed until dry, checking often on the cutting table to make sure the sides, ends were the same size. Turned out perfect! I would not be afraid to try it with that panel. I bid on one like that on ebay, but was out bid on it. Hope this helps. Good luck!