I have sat inside my car with the tailgate open and watched/photographed storms from there, I tend only to move into the car for a couple of reasons, the lightning is very close ie. no gap between flash and bang. We call them FLANGS. and rain, I hate rain, it's annoying and serves no purpose when photographing Lightning
If you are caught in the middle of a paddock during a storm and you are photographing, then thats your own fault for not checking the situation out before getting out there... But if it creeps up on you, (yes it can happen) stay low, don't lay down, keep on your feet. Having a taller object near you wont always put you in safety either.
The biggest advice I can give is understanding weather, weather patterns, storms and the local terrain. It can save your life if you can make some educated guess as what will happen.
Storm Chasing can be very dangerous, if you have doubts about it then stay home and watch it on radar.