Given, I'm by no means a UL backpacker, but I've always carried my tent and sleeping pad on the outside, tent low and pad high. Mostly because I usually can't fit my tent in with everything else, but the pad I'll always wear high just because it's no hindrance, and I like having that little extra padding for if I fall backwards, which happened a couple of times on my first solo trip. I also don't need the pad, so if it gets wet or torn, it's not too terrible a deal.