might look worse in person, but not much different than factory from the pic, remember the areas that will be hidden by the park light and headlight bezel .... which should be fitted before any welding!!
unless you're going for a real show truck, I'd think the seam sealer [holds up fine under paint] and maybe a bit of hammer work would have it looking pretty close to factory - and save having to weld up the other side to match ..... plastic filler will be visible as a difference under paint unless sealed with a couple coats of epoxy primer - and unless you're an excellent welder you'll be using filler on the welds
Bill
