I replaced some a few years ago when my trailer was rear ended. Removed the old ones. Laid them over the new ones. Marked the holes with a sharpie. Drilled new holes and reattached the new panels. The ones that weren't replaced had the screws removed one row at a time, We wheeled out those panels and reinstalled new screws. Perfect match of color (white), no. Wasn't hard, just time consuming.
Doug