Mine is welded all the way out. There is good bit of filler followed by primer and lots and lots of block sanding. Its a lot of work but worth it in the end. The guy that did mine did a great job and I witnessed a lot of the work. Body work is a bit of art I haven't mastered yet myself. BTW: The truck bed with the round notch looks sweet.
I, just like CCC stated did the same...Weld..grind. used Body filler for my bed, sanded it out...primed and painted.. it has been done now for almost 3 years and still no cracks, and its been drive everywhere!