I wonder if aluminum would rattle and be cold.
It shouldn't rattle if you use screws and some adhesive. As for being cold, the oem panels don't offer much in the way of insulation as it is. In the ones I have restored I have stuffed some foam or fiberglass insulation(paper side out or in garbage bags) between the two panels. I didn't keep the Runners long enough to see how the insulation worked, though it did quiet down the road noise quite a bit.
