Loud places excepted, this is the reason most right handed pipe welders wear soft brimmed caps (with no top button) with the brim pulled firmly down over their left ear.
IMHE nothing works very well under a vehicle as the sparks will randomly bounce a long way. Leather helps, as does buttoning up your shirt neck.
One of the protection areas often ignored is the exposure to welding UV on the neck. In the hot weather it is nicer to weld with my shirt neck open but this has caused UV burning on my neck and I am always fearful of future skin problems from repeated over exposure. I solved the problem by placing a small piece of soft leather on my mask to hang over and shield my neck. It is small enough not to be in the way when I lift my mask
Good luck, YMMV