That white molded product would work if you can find a way to attach it.
Maybe some 1x4 that was cut a little long would be able to be "convinced" to nest into the carpeting above the window frames. Get the chopsaw out and do some trial and error with some 1x.
Then the white molded product would be mounted to the top of the 1x4 if there was available clearance.
If not, then mount to the bottom of the 1x4 (or 1x3).

With this rack (white) it looks like rods can be manipulated while just reaching into the truck.....this is a big plus.
On rough roads they could bounce out unless they were twist-tied at the tips especially.

The second one pictured would require constant crawling back to manipulate the tip end. A big pain in the a$$.