As there is a prohibition of mixing meat with fish because of sakana ("danger"), I assume that if one has a small grill, one cannot grill meat and then grill fish (or vice versa) without cleaning the grill in between. However, let's say the grill has a large surface area such that a piece of meat and a piece of fish can be grilled in separate areas of the grill, and the two don't touch each other.
Can one cook the two items this way? Or are they still considered "mixed" by the fact that they are sharing the same grill and the same flame? Is there a problem with meat and fish juices dripping into the coal / rock grill area where the flame is?