For hot and wet, it's hard to beat a poncho liner for durability, warmth, and cost. It isn't the lightest item out there (~1.5 lbs for ~45º F/7º C), but they're cheap, readily available (at least here in the States), and easy to use in an hammock.

Something like that would probably be best for the temps expected. A lightweight, cheap synthetic blanket that you can use as a top quilt and not worry if you beat it up some.

Note that this assumes you've got some pack space for it (see above, regarding "synthetic"); I have no idea if you're taking more gear and need the space in your pack that down would give you.