There is no typical. It all depends on the severity of the issue. It seems your issues are "a fair amount of dents" and "oil canning". This does NOT fall into the category of panel replacement unless you have bad rust also.
It also depends on your own feeling and anxiety about an issue. It depends on the level of "restore" you envision. It depends on if you are dwelling on something that is not a big deal to live with.
"Dents" are intentionally put into large flat panels to stiffen them. They are called dimples and beading. Linear or cylindrical. these are put in before the metal is "retained" by welding or other means. Your dents/dimples were put in after. Small dents stretch small. Big dents stretch big. They may or may not have a small counter effect somewhat in strengthening the panel but not near as much as a well designed dimple before retention.
As has been said, you would have to dolly the dents carefully or heat/disc shrink them and avoid further oil canning. All without experience and at a place that offers no way to get a dolly on one side and a hammer on the other if that method is used. When someone says "it's not too hard to do" it's always hard to do for me for the first time. A large rear cab panel is way too risky for you to do any hammering or shrinking or replacement, according to the reported location, severity and type of issue.
The small dents can be filled, as said, and the oil canning stiffened by using some sort of large pieces of sheet material bonded on the inside, if it all bugs you that much. If you fill, apply thin fill to entire panel and sand down to flat. Don't fill each hole.
If it's not making noise and it is 75% covered by the bed bulkhead and not rusted......leave it alone....but you are an engineer so you can decide what makes the most sense.
