I know a number of people have asked about bed covers. A couple weeks ago at the Good Guys Del Mar show. A vender, Scotts Hot Rods had a shortbed beside their exhibit. It had a bed cover that sat flush with the top of the bedside. Asked them where they acquired it, and they told me they got it from a company called Pro's Pick. This is the web site.
https://pros-pick.com. I haven't investigated it since I'm not in the market. But it was a nice looking unit. Hope it helps someone.