Well the only way to run the stock Ram 1500 TRX wheels on the truck is to run wheel spacers. I'll grab hubcentric wheel spacers and it will be just fine. Have you run wheel spacers before? I ran them on countless cars in the past, heck I gave a set to my brother for his jetty and 70k miles later he is still driving around just fine....
Your right on the geometry of the lifts with the new trucks, I've read anything over 3in is where the binding starts with these trucks. If I was going to get a 4-6in kit I'd get new control arms to correct the geometry.