Just a quick one as it's getting late and I need some sleep. Here's a ling to a site with some very nice repaints of FSX aircraft as well as some scenery. http://www.flightsim.co.nz/
To the author of this site and many (if not all) of the skins, we have a very gifted artist that did most of the liveries for the FSX aircraft, but he didn't do all the mapping (actually very little of it). I'm pretty sure the way the fuselage and tail were done were due to limitations imposed on him for performance reasons and weren't by choice. Many of the add-on aircraft use WAY more texture space than the default aircraft and can thus easily map separate left and right sides for fuselages and tails, but we are much more conservative in our allocation of texture space for each aircraft. I hope that helps clear up the reasoning behind the limitations.