Here is the set-up I am thinking of getting.
2 x 48" tracks (mount in bottom of bed)
4 x 12" tracks (mount on the inside sidewall of bed in the back)
Plus some single stud, double stud and bolt stud fittings.
This place has all of this for a reasonable price:
L Track Tie Down - Airline Track Cargo Tie Down Rails & L Track Straps
I would get it all in powder coated black. The idea would be to use the rails in the bottom to tie down camping gear, coolers, etc. I would use one pair on the sidewall for a gas can or two and then other I would use the bolt stud fittings to mount a bottle carrier for a CO2 tank. I am not too excited about drilling a bunch of holes in the bed (worried about creating a rust initiation point), but it will meet a need.
Thoughts?