John K Jordan
My first thought was automotive emblem adhesive. The stuff is incredibly tough. Read what 3M says about it on this page: https://www.amazon.com/3M-08061-Plastic-Emblem-Adhesive/dp/B0002MID28
Good for metals, paint, plastics, all types of trim, flexible, holds in subzero to impossibly hot, holds up in years of rain or desert. I'd clean first with degreaser, soap/water, then alcohol.