I prefer the Canyon Dancer harness for trailer use... Don't have experience with using them in the back of a pick-up though. The length of your tie-downs may come into play as the harness loops do extend down from the clip-ons a good bit. I have found that when using the harness on my trailer some ratchet straps will not work.
BTW... Just as a warning, you will probably get as many opinions on this subject as you would a steering damper or motor oil thread.
BTW... Just as a warning, you will probably get as many opinions on this subject as you would a steering damper or motor oil thread.