Nice bit of thinking there.
Oh how I long for the days when I would have been just fine to sleep on a thinlight pad (not really ... I'm saving up for a NeoAir, he-he). Hats off to those that can tough it out with less.
A minor suggestion, especially if you are using a 1/8" thinlight ... consider reinforcing the areas where you put the holes. A 2"x2" piece of duct tape on each face of the pad would work well.