And then I cant decide between a single layer or double one...both works fine with a simple foam pad?

I have a double layer and a single layer and I like both. If I were using only a pad, I would prefer the DL. If using an under quilt, the SL is addequate, however I prefer a UQ on both. I have read that mosquitos can and do bite through a single layer.
Just because you don't take an interest in politics doesn't mean politics won't take an interest in you.... Pericles (430 B.C)