Piper,
Your question caught my attention partly because you have a lot more backpacking experience than I do and it goes to show the benefits of asking questions and learning. Also your questions are always interesting!
My take on it:
If it is windy enough to blow my stuff away I won’t be able to sleep without some sort of blocking mechanism. Even if temperatures are warm, just the motion of that much wind is stimulating enough to keep me awake.
Under the stars: Only if not windy. I’m not much concerned about critters. In Texas we do try to avoid ant nests, cactus, etc. If it’s hot then outside a tent is much more comfortable. Main issue is, no matter if it’s desert or whatever and the sky is clear all day and evening, it can sneak up and rain at 2 a.m. Have a shelter plan B handy.
Open tarp: Like an 8 x 10 or similar. With a polycryo groundsheet to keep excess dirt or wet off of gear. Avoid any ground that looks like it might collect rainwater. This includes spots that are clear of vegetation and stones and thus look like good spots—these spots are often clear *because* they channel or collect rain. Slight depressions in the ground surface can be hard to spot. Wind with a tarp: stake edges down, put other gear across remaining open sides. For example, pack on edge, rain jacket hung from pole and upper tie-outs, open umbrella, anything I can rig from what I have depending on the circumstances. My 8 x 10 is big enough for 1 or 2 without using bivies.
Shaped tarp (mine is a Haven2, or a Gatewood if by myself): Almost like a tent in blocking wind. But more room than a tent, and less weight to carry.
Bugs? Mosquitoes and flies bite and it’s nice to have the inner net for the shaped tarp, but then all together that makes a tent. Ants? Always around but tend to mind their own business, same with spiders and scorpions. (Texas scorpions aren’t particularly dangerous.) Caught without the inner net or a tent or just under the stars and a ton of mosquitoes show up and it’s too hot to stay in a sleeping bag? It’s happened. Solved with a whole lot of deet.
Other non-human animals, it doesn’t seem to me that a tent would make that much difference. And sleeping out, if some critter wanders near (hardly ever happens) I can see it. Humans around? Ignore them. (Or make friends.)
Stuff: Like the others have said, same organization in tarp or in the open, as in the tent. One advantage of having a minimal kit is less stuff to keep up with. Glasses, headlamp, and phone in shoes. Or under pillow if I am car camping and have a pillow. If cold, electronics like phone or camera inside the sleeping bag with me to keep their batteries warmer. Personal items ditty with stuff like chapstick and aspirin, right next to shoes, where I can easily find it in the dark. My hat is floppy so not as good for stowing things but sounds like a good idea with the right sort of hat. Cook kit, either way out yonder on top of the bear can, or if no bear or other critter concerns then just next to me or near the tarp opening, or in the shaped-tarp vestibule. Same for food bag if no need to protect. Water bottle within reach. Bandanna and socks spread out to air or dry, maybe weighted by a shoe.
If I did have a reason to stow everything instead of keeping it out handy, each item would be in the same place in my pack where it lives during the day. Always keeping every item in the same place has helped me a lot. Otherwise I lose stuff and get confused. Losing stuff especially bad since going light means no duplicates.
Another benefit of being out in the open: Â Companion starts snoring loudly, easy to pick up and move far enough away to go back to sleep!
Good discussion!