I like flat rolled out then sliced on an angle. Like take a 4" flat, roll it, then at the top start at 4" (or whatever) and taper down to 2" or one. Course that only works if you have a good flat side to work from and attach to...if the bed side is curved it takes some real layout skill. You can make a good looking fender/wheel well with a large vise and a hammer, provided you want to. Cupping is hard to do by hand but that is where slicing a taper into a rolled piece comes in.
Post some pics when you figure out what you want to do.