what to wear under your airbag

hey guys, so recently I am in the market to get an airbag and I’m pretty convinced to buy astars tech air offroad but I do have some questions about how to live with an airbag. So first of all my riding style includes both on and off road(50-50) all year around. I live in northern italy and it’s pretty cold here during winter and I usually wear 3-4 layers under my jacket but i believe with any kind of airbag vest u just can’t layer up underneath it? so I’ve been thinking about how to deal with cold and what do you guys wear under your airbag vests. Also I am planning to do long highway rides in the summer, how does the techair off road deals with summer conditions under a jacket? Its bulkiness and weight make a bad choice for warmer conditions? I appreciate every answer:) ride safe everybody