20 Foot Stock on an 8 Foot Truck ...

My solution for hauling standard 20 foot steel on my F-150 without building an aircraft carrier over the whole thing was to build 3 “Ys” out of 2”square tubing, two short for the square truck bed holes and a long one on a post on the front bumper. Here it is carrying 250 lbs. of 3 x 5 angle stock comfortably.

The only problem you might have is a more valuable truck.  You may be reluctant to drill two holes in the bumper (witha masonery bit to cut the chrome) so you’ll have to fabricate a brace to utilize the existing bumper bolts.

The three pieces fit behind the seat. I added eyes for tie down or bungy cord on the front and back but in use you don’t really need them, the stock weight keeps the front lined up and everything in place.  Although, if you ran into anything, you could be throwing 20 foot spears at whoever you hit if you don’t tie down.