Thanks all for the input....there are no 5th wheels in the future and the truck doesn't fit in the garage anyway, so I might look at the higher-profile caps.
Key purpose is to have a somewhat secure space to keep the (portable) truck box with some tools, straps, and breakdown stuff, plus space for fishing gear and camping (i.e. with tents, not "just" RV's) stuff during summers and sno-go gear during the winter.
Previously had a no-name cap on a truck long ago in a galaxy far far away that had the bars on top. Just didn't work out the same as a real rack, so that's a priority as well.
Thanks for the input and the data to consider.