Bah, I tried the 0 cellmap theory half a year ago. The best thing you can do for a mine is to make it a tough armor type that can only be defeated by itself. However, this would make the problem of ranged units never getting close enough. They'll just attack this thing and be sitting ducks...
*BTW: cellmaps SHOULD work with moving units perfectly fine, however, if I remember correctly, they cannot move if a unit is inside of them. Units can only be inside the cellmap of a unit while that unit is stopped.