Are you thinking on having multiple bikes on the truck?
I've not had experience with truck beds bike rack, but how about a tow hitch bike rack? Saves the room on your truck bed for other equipment.
Check out etrailer.com to start.
Another vote for tow hitch bike racks. That's what I use.
A friend had a bed bike rack and it was pretty good for hauling a lot of bikes around. With bungees, we were able to get 5 or 6 bikes between places safely.
There are some inexpensive fork mounts that clamp to the inside rail of a pick up that would work in a pinch, but I would not want my bikes bouncing around in the bed of a truck.
Great minds must think alike. Same set up (exactly) for my van (sans dog). Bought same design mounts at REI though.
What about like a truck pad? I drove my bike for over 6,000 miles across two countries on a Dakine Pad. It fits around five bikes, hassle free. Most come with straps to keep them down and away from each other.
I used to strap it down with my dirt bike's straps but that was less convenient and left less room on the bed for other goodies. I literally took the thing everywhere, even stopped taking it off and left it all the time. No one ever stole it, guess people most likely didn't know what it was. It was also gifted to me, so they last forever. And, now with all the new standards, those axle mount racks are always a pain when someone is sporting a different hub than you. Having a 20mm through axle, my bike never fit on those standard quick release thingies.
My two cents. Pictures below :)