Bins under the bed are fine, if you have the length. The problem comes when the pipe is 10-ft long, and the bed is 8-ft, or even 6-ft, long.
Since we carry ladders, that means a ladder rack is just a matter of time. It sure would be nice if you were able to use the space under the seats to take up the extra length.
Some pick-up truck racks have angled bins for the pipe, bins that work really well.
I had made some pipe storage atop my truck using 4" EMT. I used strut and strut straps to mount it. My roof leaked. Ordinary duct tape was plenty good for sealing the ends; sunlight would cause me replace it about once a year.
For the front .... well, Harbor Freight has a very simple $150 wood lathe that will let yo make fancier nose caps, if you want them. Make them look like missiles, really big pencils, or (with some carving) #50 Phillips screwdrivers.
For the back, closing the end is the challenge. The American Van product addresses this quite well. Screw caps get 'too tight,' too easily.
Capacities of 4" EMT, as I recall:
1/2" EMT: 2 bundles
3/4" EMT: 1 bundle
1" EMT: 6 sticks
With this in mind, I understand the appeal of a rectangular bin, rather than large pipe.