Mmm....

Intersting idea, Chris. Perhaps a few items wrapped in a lightweight wool or fleece blanket laced tight like a raost with a length of paracord, which also could serve multiple duties in a pinch. Then wrap the roll over the top and tuck into the two mesh bottle holders on each side. Then secure at the top with some sort of quick release strap or carabiner (depending upon what your pack has to clip/tie onto) so it can be quickly moved aside to open the pack without taking the whole thing off. Clever.

BTW, you'd likely want to stash the clothes in a garbage bag, another item with multiple uses, to keep them dry before wrapping in the blanket.