I don´t want land units in the water, so I came up with these small modifications:
If a non flying, non maritim resistance counter (i.e. tanks) should be placed in a sea location, roll again. If you cannot place it anywhere else than on a sea location, place it in the middle instead.
If a sea location is drawn for a space, where there is a non flying resistance counter already, draw another location until you draw a land location.