As mentioned, the bugs are the issue. I like a tent for use of the net. A tiny, light one person tent and leave the rain fly home if you don’t think you’ll need it. Just a tarp can be fine if you really don’t think there will be bugs. Then just get a light weight sleep pad(klymit makes good ones for cheap, some very minimalist. They make a Tiny pillow too that weighs almost nothing and packs down to the size of a box of matches or something like that) and a sheet like boomhauer said. I’ve used a twin flat sheet just because that’s what I had on hand and it worked fine. If cold, put on a shirt. With no cook gear, you can get pretty damn compact and light in the summer if you don’t care about comfort.