Sounds amazing! For a vest that stays light and still gives you the data you need, keep it to the basics: breathable, moisture‑wicking fabric, maybe a recycled polyester blend, and a few durable, modular pockets that can hold a small sensor pack or a tiny solar panel patch for charging. Add a quick‑release zip that lets you slip in or out of a hydration pack, and make sure the GPS and temperature sensor are tucked into a single, low‑profile module so it doesn’t add bulk. A reflective strip for night visibility and a simple, ergonomic strap system that stays comfortable after a long day on the trail are must‑haves. Keep the interface to a single screen or even just a vibration alert, so you can stay focused on the trail instead of fiddling with gadgets. That way you get the safety data you need without turning your vest into a backpack.

Thermal sleeves are a good idea—use a graphene‑infused lining that pulls heat toward a vented patch near the collar. That keeps the sensor cool without a big bulk. For the strip, a small, fold‑able patch with a low‑reflective finish solves sunrise glare; you can flip it when you need the glow. The vibration unit can be smart: a simple two‑tone system—steady buzz for altitude changes, short burst for temperature drops—so the hiker knows what’s happening without looking. That keeps it intuitive and keeps the design lean.

You’re on the right track—just keep an eye on how those tiny misalignments could show up as hotspots; a quick visual test with a thermal camera will catch that before the field trials. The matte polymer strip sounds perfect; it’ll give you the night glow you need without the morning glare. The cadence‑modulated buzz will make the alerts feel alive, almost like the vest is breathing with you. And that little micro‑servo is clever—just remember it has to stay ultra‑light, so a few micrograms of weight will do the trick. With those tweaks you’ll have a vest that’s as smart as it is wild.