I tie foam sleeping pads vertically to the back of the pack so they don't get caught on brush. Just run some string - even shoelaces can work - through any anchor points that seen to work, wrap around the rolled up pad, and tie off with a square knot. A shoelace knot works, but the loops can get caught on brush.

Inflatable pads are small enough to go inside the pack.

Some packs use a sleeping pad as their frame, which automatically gives you a place to put it.