Placing secure seats in the truck bed doesn't guarantee that rear passengers won't be hurt in an accident, or when you come to a hard stop or drive on a rough road, but seats definitely reduce the risks.
Bed Ryder seats are installed by drilling three holes in the bed to secure their framework. In addition to the frame, the unit comes with two rear-facing seats, seat belts and all mounting hardware.
Two seat designs are available. One has fold-down seat backs and lap-style seat belts (seat backs can be folded down when not in use). The other design includes racing style seats with four-point seat belts. Remove a nut and two bolts to quickly take the seats out of the bed. One stud remains, and it sticks up about an inch in the floor of the bed. The stud is close to the cab, so it may not be an issue for the way you haul cargo.
The Bed Ryder unit weights about 50 pounds. Its suggested retail price is $699.00, plus installation costs. A console/armrest is optional.
Keep in mind that laws vary from state to state -- where you live it may be illegal to ride in the back of a truck, regardless of seating and seat belts. Also, some safety organizations feel that that passengers should ride facing the rear. Check the laws and use your best judgment before hauling passengers in the back of your truck.