I have never felt that the track of my Tundra was too narrow.... If anything, its a bit wide for most trails around me. An extra 5" in track would be of absolutely no use. I could see that being different in the desert though. When you lift an IFS truck like the Tundras with simple coil overs, they tend to suck the wheels in a bit. Its simple geometry. This is usually addressed by a slight change in offset of the wheels. The Tundras come stock with an incredible amount of offset (60mm). This allows for tire clearance and the great turning radius. People run into lots of rubbing issues with larger tire widths and diameters with low offset. A proper lift along with good wheel (18-35mm) and tire selection can avoid all of these issues completely.
I cant speak for the quality of pro comps mid travel system, but I have never heard good reviews on other pro-comp products. That was in the past though. In addition to the manufactures listed above there are many more out there making these and long travel kits. For most a simple Coil over lift and upper control arms will be plenty. After that its the sheer size of the truck that is limiting in trail applications (Low break over angle, poor approach and departure angles, and a long wheelbase).
I love my Tundra for what I use it for and plan on having it a long time!