Your right on not doing just the LED bulbs. They're junk and don't put out near enough light to be seen correctly. My truck personally just has the cheap LED converted taillights that you can find off of Ebay. However when the running lights were on you could not tell the difference between the normal running light and brake light, which is a huge deal for safety. Like you said I had to installed four resistors (2 on each side) from Radio Shack into the running light circuits to dim them down to proper brightness. I tried to P.W.M. them put the wiring going into the lenses would not allow it to work correctly.
Or I believe if you want to dish out a bit more money the Recon lights may be lit correctly however I have no experience with them.