I do alot of pack hunts and rough it quite a bit and one of the best secrets I have found it soo avoid all heavy cots and matts and get a small one person blow up air matress. Down here there' s alot of pools (and of course the ocean) so most stores sell the blow up air matts for pools. They fold down to nothing and only weight a pound. At wall-mart, you might be able to find one actually made for sleeping on. It' s a little more durrable than the pool beds and come with patches in case you spring a leak. Also might be green in color in contrast to the pool beds which are usually flourecent.

That should save you some pounds. And emergency blanket or sleeping bag, allthough loud, and sometimes too hot can also save you some pounds and room in the pack but they aren' t too fun to sleep in.